V 


UNIVERSITY  OF  CALIFORNIA. 


FROM   THE    LIBRARY  OF 

,_DR.  JOSEPH 

GIFT  OF  MRS.   LECONTE. 

'  No. 


M.  BUTT  HEWSON,  C.  E.  WILLIAM  HEWSOJT,  C.  E. 

MESSRS.  M.  BUTT  HEWSON  AND  BROTHER,  CIVIL  ENGINEERS. 

HELENA,  ARKANSAS. 

The  Messrs.  Hewson  offer  their  services  as  Civil  Engineers  to  Railway 
Companies,  Levee  Commissioners,  Bridge  Companies,  and  all  other 
parties  engaged  in  the  direction  or  execution  of  Public  Works.  Designs, 
Plans,  Surveys,  Specifications,  Estimates,  Measurements,  &c.,  made  for 
all  descriptions  of  Engineering  work. 

Letters  addressed  as  above,  will  be  attended  to  with  promptness. 


PRINCIPLES    AND    PRACTICE 


OF 


EMBANKING   LANDS 


FROM  RIVER-FLOODS, 


AS   APPLIED   TO 


"LEVEES"    OF    THE    MISSISSIPPI. 


BY 

WILLIAM  HEWSON,    CIVIL  ENGINEER ; 

ASSISTED    IN     TUB    ENGINEERING     REMARKS    BY    CONSULTATION     WITH    M.    BUTT 

HEWSON,    ESQ.,  CIVIL    ENGINEER,   LATE  CHIEF    ENGINEER  OF  THE  CENTRAL 

RAILROAD  OF  MISSISSIPPI.    &C.,    4C.,    &C. 


NEW  YORK  : 

JOHN    J.    REED,    PUBLISHER, 
43  &  45  CENTRE  STREET. 

1059. 


Entered,  according  to  Act  of  Congress,  in  the  year  1858,  by 
WILLIAM  HEWSON, 

In  the  Clerk's  Office  of  the  District  Court  of  the  United  States,  for  the  Southern 
District  of  New  York. 


J.  J.  REED,  PRINTER  &  STEREOTYPER, 
43  Centre  Street,  JST.  Y 


T  O 

THE  HONORABLE  JAMES  L.  ALCORN, 

CHAIRMAN 

OF  THE  SUPERIOR  BOARD  OF 

LEVEE  COMMISSIONERS  FOR  THE  STATE  OF  MISSISSIPPI, 

&c.,     &c.,     &c., 

THIS  WOKK  IS  DEDICATED 

BY  HIS  FRIEND, 

WILLIAM    HEWSON. 


2G5 


NEW  YORK,  SEP.  15th,  1858. 

To  the  Hon.  James  L.  Alcorn,  } 

Of  Mound  Place,  Coahoma  County,         > 

MISSISSIPPI.  ) 

MY  DEAR  SIR  : — 

As  father  of  the  Levee-system,  in  at  least  that  State,  you  are, 
on  public  grounds,  the  man  of  all  others  to  whom  ought  to  be 
dedicated  the  following  results  of  my  reflections  and  labors  on 
the  Levees  of  Mississippi.  As  a  Legislator,  as  a  County 
Commissioner,  as  a  general  Commissioner,  for  the  conduct  of 
those  improvements,  your  zeal,  energy,  and  talent,  have  con- 
tributed, in  an  eminent  degree,  to  the  present  matured 
prospects  of  the  most  important  material  interests  of  your 
State — the  drainage  and  reclamation  of  the  great  Valley  of 
the  Yazoo.  As  an  agent,  under  your  direction,  in  the  accom- 
plishment of  that  great  result,  I  am  bound,  therefore,  to  lay  at 
your  feet  this  summary  of  the  views  and  rules  by  which  I  have 
been  guided  in  that  agency. 

As  a  private  friend,  however,  you  of  all  my  friends  in  this 
country,  have  the  first  claim  on  my  feelings.  Truthful,  warm, 
and  disinterested,  as  I  have  ever  found  you  in  our  long  and 
somewhat  trying  intercourse,  it  affords  me  cordial  pleasure  to 
give  public  evidence,  by  even  the  dedication  of  this  vol- 
ume to  you,  of  my  profound  conviction  of  your  truth,  warmth, 
and  disinterestedness  as  a  private  friend. 

While  your  qualities  of  head — in  the  capacity,  the  courage, 


6 

the  integrity,  with  which  you  have  managed  the  public  inter- 
ests  committed  to  your  care — command  my  unqualified 
respect,  it  is  privately  a  pleasure  to  me — as  publicly  it  is  a 
duty — to  inscribe  to  you,  as  I  here  do,  this  result  of  my  expe- 
rience and  reflection  on  River-embankment.  Accept  it,  my 
dear  Colonel,  as  an  humble  expression  of  the  honest  regard  of 
your  ever  faithful  friend, 

WILLIAM   HEWSON. 

P.  S.  Two  years  ago,  this  volume  was  commenced  ;  though 
in  the  intervals  of  leisure  occurring  under  active  engagements 
of  my  mind,  it  had  not  been  completed  until  to-day. 


PREFACE, 


IMMENSE  public  wealth  is  being-  accumulated  behind 
the  Levees  of  the  Mississippi.  From  Cairo  to  the  Balize, 
millions  of  acres  of  the  finest  land  in  the  world  are  being 
reclaimed  from  the  Bear  and  the  Panther,  to  bring*  forth 
fruit  for  the  enrichment  of  the  American  Union,  and  the 
luxury  of  private  industry.  Millions  of  money  have 
already  been  expended  on  the  works,  behind  which  this 
great  investment  of  enterprise — of  labor  and  capital — is 
going  on ;  and  yet.  up  to  the  present  hour,  these  expendi- 
tures have  been  made,  to  a  great  extent,  without  regard 
to  the  teachings  of  a  regularly  digested  experience.  This 
book — devoted  to  the  Levee,  and  to  Levee  interest — is, 
therefore,  given  to  the  public,  the  first  attempt  to  reduce 
to  order  and  to  rule,  the  design,  execution,  and  measure- 
ment of  the  Levees  of  the  Mississippi.  Hundreds  of 
thousands  of  people  are  concerned  to  the  extent  of  their 
fortunes — if  not,  even  of  their  lives — in  the  subject  treat- 
ed of  here ;  and  hence  is  it  unnecessary  for  the  author  to 


8  PREFACE. 

apologize  to  the  public,  for  an  attempt  to  reduce  a 
subject  of  such  immense  importance  to  an  exact  popular 
rationale. 

The  necessities  of  a  country  so  new  as  that  along-  the 
Mississippi,  place  the  management  of  its  public  works  in 
the  hands  of  unskilled  men.  This  fact,  coupled  with 
others  proper  to  the  case,  commits  the  execution  of  the 
Mississippi  Levees  to  the  inexperienced  good  sense  of 
the  planter,  or,  less  safe  guide,  to  the  inexperienced 
manipulations  of  the  laborer,  the  wood-chopper,  the  me- 
chanic, who  succeeds  in  obtaining  from  that  planter 
employment  as  a  Civil  Engineer.  This  condition  of 
things,  is,  under  all  the  circumstances  of  the  case,  to 
some  extent  unavoidable;  and  in  order,  therefore,  to 
make  it  comport  as  far  as  possible  with  the  proper  man- 
agement of  the  Levees,  this  summaiy  of  the  principles 
and  practice  of  Leveeing,  is  made  in  terms  equally  intel- 
ligible to  the  professional  short-comings  of  those  "  En- 
gineers," and  to  the  popular  knowledge  of  those 
planters. 

Those  gentlemen  who,  engaged  on  the  Mississippi 
Levees  are,  in  fact,  Civil  Engineers,  will  doubtless 
receive  this  humble  volume  favorably.  They  will,  it  is 
hoped,  find  something  in  it  that  may  assist  their  labors 
directly,  and  much  that  will  tend  to  strengthen  their 
influence  over  the  works,  by  convincing  the  intelligent 
planter,  that  those  works  are  subjects  of  extensive  reflec- 
tion and  experiment  in  a  certain  department  of  know- 
ledge. 

This  Memoir,  humble  as  it  is  in  its  pretensions,  will 
do  good  service  to  the  profession,  and  to  the  public,  if  it 


PREFACE.  9 

assist  the  parties  interested  in  Levees  to  discriminate 
between  the  educated  Engineer  and  the  untrained  pre- 
tender. 

This  volume  contains  a  short  review  of  the  History  of 
Embankments.  Natural  Phenomena  of  Rivers  have  also 
been  considered  in  it  briefly,  especially  those  phenomena 
bearing-  more  directly  on  the  theory  of  Leveeing.  The 
Engineer  and  Levee  Commissioner  will  find  these  heads 
of  some  value  for  their  own  guidance,  and  also,  in  obtain- 
ing that  co-operation  for  their  plans,  which  must  always 
follow  from  enlightening,  on  the  subject  of  those  plans, 
the  population  living  behind  the  Levees. 

The  principles  of  Economy  and  Usefulness,  touched  on 
in  this  part  of  the  subject,  will  be  of  great  importance  to 
the  Engineer  and  to  the  Commissioner,  in  indicating  use- 
ful reforms  in  the  present  system  of  Levee  management 
and  construction. 

The  Earth-work  tables  included  in  the  following  pages, 
will  be  found  of  general  interest.  They  embody  a  new 
system  of  obtaining,  by  inspection,  the  areas  of  Earth- 
works in  exact  accordance  with  the  prismoidal  formula. 
They  are  alike  applicable,  as  far  as  they  extend,  to  the 
prisms  of  the  Levee-bank,  the  Canal-bank  or  cut,  the 
bank  or  cut  of  the  Railroad.  For  slopes  of  a  varying 
rate,  or  of  greater  extent  than  those  given  in  the  tables, 
the  plan  pursued  in  the  preparation  of  those  tables  is 
equally  applicable ;  and  is,  therefore,  highly  valuable  to 
the  practical  Engineer,  as  a  means  of  -simplifying  to  an 
extraordinary  extent,  the  laborious  reference  necessary 
in  such  tables  as  Sir  John  McNeill's,  for  calculating  quan- 
tities by  the  prismoidal  formula. 


10  PKEFACE. 

The  Contractor  on  Levees  is  highly  interested  in  the 
publication  of  the  Earth-work  tables  included  in  these 
pages.  Ignorance  and  carelessness  have,  too  generally, 
characterized  estimates  of  the  quantities  of  Earth-work 
executed  in  Leveeing ;  the  consequence  being,  some- 
times, large  losses  to  the  contractor,  sometimes  large 
losses  to  the  public.  These  tables,  placing  the  facts 
within  the  reach  of  both  parties,  guarantee,  therefore, 
justice  in  all  cases  to  each.  The  use  of  the  tables  as 
explained  in  the  letter-press,  is  short  and  simple.  Men 
of  ordinary  intelligence,  knowing  the  heights  of  a  Levee, 
at  intervals  of  100  feet,  can  tell  with  accuracy  by  those 
tables  the  solid  content  of  the  Levee.  The  Commissioner, 
the  Engineer,  the  Contractor,  and  the  Public,  can,  there- 
fore, bring  these  results  within  the  compass  of  the  popu- 
lar knowledge. 


CONTENTS.  11 


CONTENTS. 


CHAPTER  I. 
SKETCH  OF  THE  HISTORY  OF  EMBANKING, 13 

CHAPTER   II. 
NATURAL  PHENOMENA  OF  RIVERS,        ......  22 

CHAPTER   III. 

THE  LEVEE, 53 

CHAPTER   IV. 

DETAILS  OF  LEVEE  WORKS,        . 79 

CHAPTER    V. 

HIGH  WATER  MARK, 102 

CHAPTER    VI. 

LOCATION,  106 

CHAPTER    VII. 

SURVEYS, ' 116 

CHAPTER    VIII. 
ADMINISTRATION, 121 

CHAPTER    IX. 
EARTH-WORK  CALCULATIONS, 134 

THE  TABLES  .  153 


PRINCIPLES  AND  PRACTICE 


OF 


EMBANKING  LANDS  FROM  RIVER-FLOODS. 


CHAPTER  I. 

SKETCH  OF  THE  HISTORY  OP  EMBANKING. 

"  LEVEEING  " — Embanking  as  it  is  generally  called — to  confine 
rivers  within  their  banks,  and  bar  the  approach  of  the  sea,  and 
its  sister  system  of  back-drainage,  have,  from  a  very  early 
period,  occupied  the  attention  of  individuals,  governments  and 
peoples. 

The  Phcenecians,  Babylonians,  Egyptians,  Eomans,  Hindoo- 
stanees,  and  other  East  Indian  nations,  embanked  low  lands  and 
drained  marshes.  Those  nations  chiefly  inhabited  alluvial 
plains,  which,  by  their  superior  richness  of  soil  when  reclaimed, 
amply  repaid  them  in  the  abundance  of  their  crops,  at  less 
labor  than  was  necessary  to  expend  in  the  cultivation  of  higher 
districts.  History  informs  us  that  the  Babylonians  and  Egypt- 
ians were  the  first  to  adopt  the  system  of  reclaiming  waste 
lands  by  embankments. 

The  low  ground  in  the  midst  of  which  the  city  of  Babylon 
was  built,  affords  an  early  instance  of  the  necessity  of  embank- 
ing ;  and  consequently  taught  its  inhabitants  the  principles  of 
construction  in  earth  works.  The  causeway  thrown  up  over  the 


14  PKINCIPLES  AND   PRACTICE   OP 

low  grounds,  on  each  side  of  the  Euphrates,  leading  to  the  cel- 
ebrated bridge  over  that  river,  is  the  most  remarkable,  because 
it  is  the  most  ancient,  of  which  there  is  any  record. 

Egypt,  the  land  of  floods  and  marshes,  from  the  richness  of 
its  soil  when  reclaimed,  was  enabled  at  known  periods  of  his- 
tory to  supply  during  times  of  dearth  the  impoverished  nations 
around  with  corn.  Egypt,  when  subject  to  Rome,  was  the 
granary  from  whence  supplies  for  that  city  were  drawn.  About 
2320  years  before  the  Christian  era,  the  greater  part  of  Egypt 
was  an  extensive  marsh,  which  Men6s,  the  then-reigning 
King,  undertook  to  reclaim.  He  diverted  the  course  of  the 
Nile  into  the  middle  of  its  valley  or  "  bottom  lands  ;"  cut  water- 
courses and  raised  embankments  to  confine  the  waters  within 
them.  His  successors,  each  in  his  turn,  made  similar  improve- 
ments— raised  mounds  on  which  to  build  their  cities,  above 
overflow,  and  cut  canals  for  irrigation.  The  celebrated  Lake 
Mceris  is  represented  as  one  of  the  most  remarkable  works  of 
ancient  Eygpt ;  and  is  supposed  to  have  been  executed  by  a  King 
of  that  name ;  and  finished  about  1385  years  B.  C.  This  Lake  was 
according  to  Herodotus  450  miles  in  circumference,  and  is  said 
by  some  to  have  been  in  places  300  feet  deep.  *  By  means  of 

*  This  summary  of  the  great  drainage  works  of  the  past  follows  without  question 
the  statements  of  History.  Here,  however,  it  may  be  observed  that  this  Lake  Mceris 
story  seems  to  be  one  of  the  most  preposterous  inventions  of  even  Herodotus.  The 
pumping  necessary  to  keep  such  an  excavation  dry  is  with  even  all  the  appliances 
of  steam  an  inconceivable  feat.  The  lifting  and  moving  performances  of  the  ancient 
Egyptians  are  truly  wonderful,  but  how  they  could  have  hauled  the  infinite  volume 
of  excavation  from  such  a  "pit"  as  Lake  Mceris,  with  an  average  haul  of  some  30 
miles  is  beyond  all  comprehension.  Waiving,  however,  these  difficulties,  the  story  is 
absurd.  At  an  average  depth  of  150  feet^-one-half  the  aUeged  maximum  depth— 
the  earth  moved  from  Moeris  would  represent  a  content  of  2,400,000  millions  of  cubic 
yards.  Supposing  the  Egyptians  furnished  with  the  improved  tools  of  modern  ex- 
cavations, this  work  at  the  rate  of  5000  cubic  yards  per  man  per  year,  would  have 
consumed  for  "loosening  and  lifting"  the  labor  for  12  months  of  480  millions  of  men. 
Done  as  stated  in  the  reign  of  King  Moeris,  if  it  be  supposed  that  he  reigned  for  even 


EMBANKING  LANDS  FEOM  RIVER-FLOODS.  15 

a  canal  it  was  supplied  with  water  for  six  months  in  the  year — 
this  water  during  the  remaining  six  months  returning  to  the 
river  by  a  regular  system  of  irrigation  throughout  the  whole 
extent  of  Egypt ;  thus  supplying  the  land  with  moisture  during 
the  dry  season.  This  Moeris  Canal,  in  itself  a  stupendous 
effort  of  art,  is  still  entire.  It  is  40  leagues  in  length.  There 
were  two  others  also  in  connection  with  the  lake  having  sluices 
which  were  shut  and  opened  alternately  as  the  waters  of  the 
Nile  varied  in  elevation. 

The  ancient  Romans  were  more  remarkable  for  the  extent  of 
their  embankments,  and  the  energy  and  skill  put  forth  for  the 
reclamation  of  submerged  lands,  than  any  other  nation  before 
their  time.  They  appear  to  have  been  the  special  guardians 
of  the  swamps  and  marshes  of  Europe.  The  inducements  to 
this  guardianship  lay  in  the  great  superiority  and  richness  of 
those  soils  as  compared  with  the  more  elevated  districts. 

The  Romans  embanked  the  Tiber  near  Rome,  and  confined 
the  waters  of  the  Po  in  a  similar  manner  for  many  miles  from 
its  embouchure.  Remains  of  their  embankments  are  to  be 
found  in  Holland,  in  most  of  the  Fen-districts  of  England,  and 
in  other  countries  where  their  indomitable  energy  and  perse- 
verance carried  them. 

India  presented  originally  great  difficulties  to  culture.  Its 
physical  and  its  atmospheric  character  combine  to  present  for- 
midable draw-backs  to  natural  production.  Consisting  largely 
of  alluvial  flats,  the  suddenness  of  its  monsoon-rains,  the  short 
duration  of  those  rains,  and  the  long  duration  of  the  succeed- 
ing drought,  place  cultivation  completely  subject  to  these  two 
conditions — irrigation  at  one  season  of  the  year,  and  drainage 
at  another.  Embankment  is  the  prime  means  by  which  these 

48  years,  the  work  must  have  employed  for  that  period  in  digging  alone  10,000,000 
of  able  bodied  laborers !  50  millions  of  people  must  therefore  have  lived  on  the  works, 
and  a  like  number  have  been  employed  feeding  them. 


16  PRINCIPLES   AND   PRACTICE  OF 

have  been  accomplished  ;  and  these  embankments,  or,  as  they 
are  called  in  Hindostan,  "  Bunds,"  are  the  great  artificial  agents 
that  have  conferred  the  teeming  luxuriance  of  the  present 
state  of  that  country  on  the  soil  of  India.  The  "  Bunds"  of 
India,  while  damming  back  the  flools  of  the  monsoons  from  the 
rich  flats  behind  them,  run  in  double  lines  ;  and  by  confining 
between  them  the  waters  of  those  floods,  reticulate  Hindostan 
with  numberless  canals.  Naturally,  these  waters  would  escape 
at  periods  of  overflow,  through  a  few  rivers  ;  but,  distri- 
buted through  numerous  canals,  they  are  retained  on  their 
passage  to  the  sea  sufficiently  long  to  answer  through  the  dry 
season  the  purposes  of  irrigation.  To  husband  the  too-copious 
monsoon-rains,  the  natives  have  built  "  Bunds"  of  great  magni- 
tude across  river-vallies  and  streams,  thus  forming  artificial 
lakes  or  reservoirs,  often  of  vast  extent,  as  storehouses,  to 
supply  the  wants  of  a  dry  season.  From  these  the  water  is 
conducted  for  miles  along  the  flanks  of  mountains,  across 
gorges '  and  vallies,  and  through  the  most  difficult  countries, 
irrigating  the  land  in  its  descent.  Taught  by  the  necessities 
of  their  country,  the  East  Indian  nations  of  by-gone  ages  have 
left  behind  them  the  remains  of  works  of  irrigation — monu- 
ments of  their  greatness — unsurpassed  even  by  Egypt.  One 
of  these  on  the  Island  of  Ceylon,  an  evidence  of  the  enterprise 
and  public  spirit  of  the  Cinghalese  monarchs,  is  a  good  speci- 
men of  such  works.  It  was  formed  of  huge  blocks  of  stone, 
strongly  cemented  together  and  covered  over  with  turf,  a  solid 
barrier  fifteen  miles  in  length,  one  hundred  feet  wide  at  base, 
sloping  to  a  top  width  of  40  feet,  and  extending  across  the 
lower  end  of  a  spacious  valley. 

Egypt  was  undoubtedly  the  cradle  of  the  sciences,  and  par- 
ticularly Hydraulics.  It  remained,  however,  for  later  times  to 
arrange  the  laws  of  fluids  into  well  defined  formula.  This 
science  seemed  to  lay  dormant  for  many  hundred  years  ;  and 


17 

it  was  not  until  during  the  eleventh  and  twelfth  centuries,  when 
it  was  thought  necessary  to  make  several  of  the  Italian  rivers 
navigable,  and  to  cut  canals  for  drainage  and  irrigation,  and  in 
the  thirteenth  century x,when  the  practice  of  embanking  and 
confining  the  rivers  of  Italy  within  their  banks,  was  adopted, 
that  it  can  be  said  to  have  claimed  the  attention  of  the  learned. 
Before  the  seventeenth  century  there  was  scarcely  any 
known  digest  of  principles,  by  which,  to  carry  out  the  works 
of  the  Hydraulic  Engineer. 

In  the  year  1665,  a  Congress  of  the  most  celebrated  scien- 
tific men  met  in  Tuscany.  At  this  Congress  it  was  proposed 
by  Cassini  and  Yiviana,  to  confine  the  Chiana  by  banks,  and 
so  conduct  it  to  the  Arno.  During  a  subsequent  meeting,  at 
which  Torricelli  was  present,  the  embankment  of  the  Chiana 
was  recommended  on  the  ground  that  the  rivers  Arno,  Tiber, 
and  Po,  were  confined  by  the  same  means.  At  this  period, 
practical  Hydrodynamics  received  a  great  impetus ;  congres- 
sional meetings  of  scientific  men  were  held,  which,  under  the 
necessity  of  reclaiming  all  the  submerged  lands  of  Italy,  called 
out  the  energies  and  talents  of  a  host  of  the  ablest  philoso- 
phers of  the  age.  The  experience,  experiments  and  writings, 
brought  forth  under  these  circumstances  laid  the  foundation 
of  our  knowledge  of  Hydraulics  in  nearly  all  its  branches. 
Amongst  the  distinguished  men  contributing  at  that  time  to 
this  subject,  were  Gallileo,  Torricelli,  Guglielmmi,  Poleni, 
Manfredi,  Zendrini. 

A  general  system  of  embanking  rivers,  as  a  consequence  of 
this  movement  amongst  the  savans  of  the  day,  was  adopted  in 
Italy,  so  that  the  Po,  Adige,  Tiber,  Arno,  Reno,  and  their 
tributaries  are  now  confined  between  high,  artificial  banks. 

Italy,  from  the  peculiarity  of  its  physical  character,  seems 
adapted  by  nature  for  the  cultivation  of  this  science.  Lofty 
mountains,  frequent  rain-falls,  heavy  snow-drifts,  break  the 


18  PRINCIPLES   AND   PRACTICE   OF 

region  of  the  Alps  and  Appenines  into,  frequently,  foaming 
torrents,  torrents  that,  descending  with  headlong  impetuosity 
to  the  more  level  country  on  the  sea-board,  pour  destruction 
upon  town  and  field.  Along  the  low  lands  of  the  Po,  perhaps 
the  most  fertile  section  of  all  northern  Italy,  from  the  destruc- 
tive character  of  its  precipitous  floods,  immense  changes  have 
taken  place  from  time  to  time.  The  river  has  frequently 
changed  its  course,  filling  lakes  and  marshes,  destroying  towns, 
and  causing  immense  devastations.  Hydraulic  Engineering 
has  executed  its  first  systematic  works  on  the  drainage  of  the 
Po  ;  and  the  nations  of  modern  Europe  have  received  there- 
from, knowledge  which  enabled  them  to  carry  on  similar  works. 
France,  Spain,  Holland,  Germany,  England  and  Ireland,  are 
thus  alike  indebted  in  this  department  of  practical  science  to 
Northern  Italy.  And,  now,  embankments  which  reclaim  im- 
mense bodies  of  rich  land  abound  throughout  all  Europe. 

Holland  is  well  known  to  be  low  and  flat.  The  alluvial  de- 
posits brought  down,  before  even  the  dawn  of  History,  from 
the  higher  districts  of  Western  Germany  and  Northern  France, 
by  the  Scheldt,  the  Meuse,  and  the  Rhine,  resulted  in  a  marine 
swamp,  known  now  as  the  "Low  Countries."  This  once  salt- 
marsh  has  been  erected  into  the  rich  and  prosperous  Kingdom 
of  Holland  by  "Dikes"  or  embankments.  De  Luck,  in  the  first 
volume  of  his  Geological  Travels,  says,  "  that  the  sea  banks  on 
the  coast  of  the  North  sea,  at  the  mouths  of  the  Eyder  and  Elbe, 
extend  to  not  less  than  350  miles."  And  by  another  author, 
"  the  Southern  shore  of  the  North  sea  is  embanked  to  the  ex- 
tent of  600  miles,  the  Southern  shore  of  the  Baltic  for  1000 
miles,  and  the  Bay  of  Biscay  to  the  extent  of  300  miles."  All 
the  great  rivers  of  Germany  and  Holland,  such  as  the  Rhine, 
the  Elbe,  the  Oder,  the  Leek,  the  Yaert,  the  Yssel,  the 
Maes,  have  all  been  confined  to  their  channels  by  embank- 
ments. 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  19 

The  Zealand  Dikes  or  embankments  are  said  to  be  at  least 
300  miles  in  extent,  and  to  cost  for  annual  repairs,  the  large 
sum  of  $800,000  !  The  sum  expended  for  similar  objects  and 
for  the  regulation  of  the  Vater-levels  throughout  Holland  alone, 
amounts  to  $3,000,000  per  annum  !  The  early  history  of 
embanking  in  Holland,  Zealand,  and  other  places,  presents  a 
series  of  calamities  from  the  destructive  power  of  water, 
almost  unparalleled  in  history. 

England  is  probably  indebted  to  the  Romans  for  the  first 
embankments  on  the   Thames.      "  London"  indicates  by  its 
derivation  from  the  Saxon  words  "  Lyn  din,"  that  it  was  once 
"  the  City  of  the  Lake."    And  history  tells  us  that  it  owes  its 
existence  to  the  drainage  of  its  site  ]by  embankments.     The 
fact,  however,  may  be  settled  without  an  appeal  to  history.     It 
is   well  known  that  many  of  the  marshes  in  the  immediate 
vicinity  of  London — now  tinder  consideration,  as  subjects  for 
embankment,  are  12  feet  below  high  tide  in  the  Thames.     The 
original  marshy  character  of  the  ground  on  which  the  modern 
Babylon — like  the  ancient  Babylon — stands,  is  indicated   also 
by  the  fact,  that  many  of  its  streets  terminate  with  the  word 
"  Wall  ;"  the  names  of  several  towns  and  places,  such  as  Black- 
wall,  Mill-wall,  &c.,  on  the  Thames,  are  compounds  of  the  same 
word,  which  in  Kent,  and  Essex,  is,  to  this  day,  the  popular 
name  for  embankment.     It  is  stated  in  an  article  published  in 
the  "  Builder"  of  22d  August,  1857,  headed,  "  Two  Aspects  of 
London  ;"  that  "  All  the  space  which  is  now  so  thickly  covered 
with  vast  works,  and  occupied  with  living  multitudes,  was  a 
watery  waste,  as  desolate  as  the  neighborhood  of  Babylon  at 
the  present  day.     Standing  on  a  high  part  of  Clerkenwell,  or 
Islington,  it  is  easy  to  imagine  the  picture  ; — a  foreground  of 
sedges,  reeds,  and  willows.     On  the  South  East  and  West,  a 
space  of  water  extends  to  the  base  of  the  high-lands,  present- 
ing the  appearance  of  a  large  lake  in  which  the  channel  of  the 
Thames  is  not  even  defined  1" 


20 


PRINCIPLES  AND  PEACTICE  OP 


The   commencement  of  modern  embankments  in  England, 
took  place   under    Cromwell,  about  the   middle  of  the  17th 
century.     In  1478,  however,  the  works  undertaken  by  Bishop 
Morton,   and   subsequently   completed  by    Charles  the  First, 
conjointly  with  the  Earl  of  Bedford,  and  his  friends,  reclaimed 
1,033,360  acres  of  rich  land.    In  the  space  of  a  few  years, 
previously  to   the  year   1651,   about  425,000   acres   of  fens, 
morasses,  or  overflowed  lands,  were  recovered  in  Lincolnshire, 
Cambridgeshire,  Hampshire,  and  Kent.     Through  the   exer- 
tions of  Sir  Cornelius  Yermuyden — a  Zealander,  who  confined 
the  Welland,  and  the  Ouse  within  artificial  embankments,  a 
district  has  been  reclaimed  from  the  sea,  in  England,  larger 
than   the  whole  Kingdom  of  Holland.     Sir  John  Eennie,  in 
conjunction  with  Mr.  Telford,  constructed  the  celebrated  Nene- 
outfall,  which,  with  the  aid  of  banks,  drained  immense  bodies 
of  rich  land.    Mr.  Wiggins  says,  that  "  the  embankments  on 
the  coast  of  Essex  alone,  measure  220  miles."    The  principal 
rivers  in  England,  subject  to  heavy  freshets,  are  all  embanked, 
the  Thames,  the  Mersey,  &c. 

Of  late  years,  embanking  overflowed  lands  has  been  carried 
on  extensively  in  Ireland  ;  and  in  connection  with  the  drain- 
age of  those  lands  by  deepening  the  beds  of  the  principal 
rivers  and  their  tributaries,  has  been  done  almost  exclu- 
sively by  the  Government,  at  the  expense  of  the  owners  of  the 
improved  lands. 

This  summary  of  the  historical  facts  of  embanking  is  required, 
by  the  conciseness  necessary  in  presenting  the  subject  here, 
to  be  thus  brief  and  general.  Dugdale's  history  of  embank- 
ing— an  English  work  of  great  merit,  will  furnish  the  curious 
with  the  details  of  this  great  head  of  National  industry  ;  but 
sufficient  has  been  here  said,  to  indicate  the  extent  to  which 
the  subject  of  Leveeing  may  be  considered  within  the  pale 
of  practical  science,  and  extensive  practical  experience. 


. 
EMBANKING  LANDS  FROM  RIVER-FLOODS.  21 

Individual  observation  however  extended  will  not,  there- 
fore, be  brought  by  really  intelligent  men  into  conflict  with 
the  teachings  of  a  knowledge  contributed  to  by  so  many 
distinguished  men,  and  tested  by  so  many  centuries  of  actual 
practice. 


22  PRINCIPLES  AND   PRACTICE  OF 


CHAPTER    II. 

THE   NATURAL  PHENOMENA   OF  RIVERS. 

LEVEES  on  the  Mississippi  are  both  important  and  costly. 
Works  involving  so  much  public  and  private  interest,  and  so 
much  public  and  private  outlay,  ought  to  be  predicated  on 
principle.  To  oppose  the  laws  governing  a  mighty  river,  is  a 
labor  from  which  even  the  Hercules  of  American  energy  may 
well  recoil,  and  therefore  does  it  become  a  duty  of  common 
sense  to  place  that  energy,  in  dealing  with  the  Mississippi,  at 
a  labor  in  the  least  possible  discord  with  those  laws.  To  do 
this,  it  becomes  necessary  in  the  first  place,  to  study  the  habits 
of  rivers  generally,  and  of  the  Mississippi  particularly  when 
its  habits  are  separated  from  those  other  rivers  by  specialities. 
The  particular  habits  of  the  Mississippi  may  be  made  subjects 
of  local  observations  ;  but  in  order  to  confine  the  sphere  of 
those  observations  to  its  proper  limits,  and  to  assist  in  its  in- 
ferences, it  is  necessary  to  consider  here  in  popular  terms,  the 
general  rules  affecting  the  regime  of  rivers  as  applied  specially 
to  the  Mississippi. 

Science  is  acquainted  but  generally  with  the  causes  by  which 
river  phenomena  are  influenced  or  the  complicated  laws  by 
which  they  are  governed.  The  little  success  that  has  attended 
the  labors  and  reflections  of  enquirers  on  this  subject  from  the 
time  of  Gallileo,  is  attributable  to  the  difficulty  of  making  cor- 
rect observations,  and  to  the  local  specialities  which  exist  in 
most  rivers.  The  following  review  contains  a  summary  of  the 
exact  laws,  and  approximate  rules  deduced  from  observations 
of  rivers. 


EMBANKING  LANDS  FROM  EIVER-FLOODS.  23 

The  surface  of  a  country  may  be  generalized  into  a  series  of 
inclined   planes — those   planes   ascending   from  the  sea-level 
at  the  shore,  to  the  mountain-heights  of  the  interior.     In  a 
paper  drawn  up  for  the  Institute  of  Civil  Engineers  by  Mr.  M. 
Butt  Hewson,  explanatory  of  the  system  pursued  by  him  in 
carrying  out  certain  works  for  the  Board  of  Public  Works  in 
Ireland,  the  hydrographical  distributions  of  rain-shed  are  thus 
indicated  :     "  The   surface  of  a  country  is   resolved  by   its 
drainage-waters  into  several  systems  of  vallies.     These  vallies 
are  termed  by  Engineer's  rain  or  "  catchment "  basins.   The  line 
of  lowest  level  in  each  of  these  is  traced  by  a  stream  •  this 
stream  tends  to  its  debouching  point,  more  or  less  tortuously, 
more  or  less  inclined.     A  catchment-basin  is  generally  resolv- 
able into  several  minor  vallies  associated  together  by  the  direct 
discharge  of  their  respective  streams  into  one  common  outlet  ; 
the  several  points  of  this  discharge  marking  the  several  stages 
of  increase  in  the  area  of  the  basin.     A-  great  central  valley 
traverses  the  lowest  level  of  these  river-basins,  secondary  vallies 
branching  from  each  side  of  this,  constituting  in  their  turn 
central  vallies  to  distinct  portions  of  the  whole  catchment. 
Tertiary  vallies — so  to  speak — branch  again  from  these  second- 
ary vallies,  and  like  those  secondaries,  become  so  many  distinct 
trunks  to  so  many  distinct  systems  of  branch  vallies.     And  so 
on  until  the  sources  of  mighty  rivers  are  traced  on  all  sides  of 
their  basins,  into  the  ravines  of  far  off  ridges,  and  the  gorges  of 
snow-capped  mountains."     The  physical  features  of  a  country 
being  of  this  character,  the  fact  of  rain-falls  results  necessarily 
in  the  facts  of  Cascade,  Rapid,  Stream,  Rivulet,  and  River. 
Drawn  up  by  that  great  mechanical  agent,  Heat — evaporating 
water  from  the  surface  of  the  earth  and  of  the  sea — water-laden 
clouds,  driven  and  distributed  by  the  winds,  are  by  various 
causes  precipitated  on  the  land  ;  and  bursting  over  any  portion 
of  a  country  their  waters  are  congregated  by  gravity  from  the 
higher  into  the  lower  vallies,  and  collecting  strength  as  they 


f  PRINCIPLES   AND   PRACTICE   OF 

rush  down  their  several  inclined  planes,  push  forward  in  their 
downward  course,  over  cataracts,  down  rapids,  through  lakes, 
and  gently  sloping  streams,  till  uniting  in  one  common  grand 
volume  in  the  primary  valley,  they  roll  forward  to  the  sea,  in 
the  power  and  magnificence  of  a  Mississippi,  an  Amazon,  a 
Ganges,  or  a  Nile.  The  amount  of  water  thus  falling  upon  the 
earth  is  not  less  than  thirteen  hundred  millions  of  gallons  per 
second  throughout  the  year  ;  one-half  of  this  quantity  is  be- 
lieved to  run  off  the  surface  of  the  earth  directly  in  rivers, 
which  is  the  cause  of  floods,  one-fourth  is  evaporated  and  taken 
up  by  vegetation,  and  the  remaining  fourth  passes  into  the 
earth,  keeping  up  a  constant  supply  to  the  numerous  springs 
which,  to  a  great  extent,  feed  and  preserve  the  summer  flow 
of  water-courses. 

Large  and  small  rivers  are  governed  by  the  same  laws,  under 
the  same  circumstances.  The  smallest  rivulet  has  its  own 
catchment-basin,  or  fain-shed,  corrodes  the  bank  that  confines 
it,  and  pushes  forward  towards  the  sea,  in  proportion  to  its 
strength,  the  matter  thus  detached  and  held  in  mechanical 
suspension  by  the  rushing  of  its  waters.  This  smallest  rivulet 
is  characterised  by  its  overflows,  its  sand-bars,  eddies,  sinuosi- 
ties, and  siltings-up  of  bed  along  its  course,  and  at  its  mouth, 
in  precisely  the  same  manner  as  the  great  "  father  of  waters," 
or  any  of  the  other  mighty  water-courses  of  the  earth. 

The  course  of  all  rivers  is  so  devious  that  the  distance 
between  their  extremities  is  very  frequently  twice  the  length 
of  their  rectilinear  distance.  Every  obstacle  or  projection  in 
the  bank  where  the  soil  is  harder  and  of  a  more  resisting 
nature,  the  slightest  irregularities  in  the  bottom  and  sides, 
partially  obstruct  its  course  ;  and  according  to  the  magnitude 
of  that  projection,  deflects,  or  tends  to  deflect,  the  current  to 
the  other  side.  This  deflection  of  the  current  produces  a 
circular  motion  in  the  water,  which  acting  on  the  soft  portions 
of  the  bank,  hollows  it  out,  forms  eddies,  and  accelerates 
change  in  the  direction  of  the  current. 


EMBANKING   LANDS  FKOM  EIVER-FLOODS.  25 

Overflows  or  freshets,  in  rivers  are  very  variable  in  volume. 
They  are  dependent  upon  a  variety  of  causes  being  brought 
to  bear  to  produce  them.  Heat  and  cold,  clouds  and  winds, 
forests  and  mountains,  as  first  causes,  are  all  intimately  connect- 
ed with  their  origin  ;  cultivated  lands,  dense  forests,  water- 
bearing strata,  and  rocks  of  a  permeable  and  of  an  impermeable 
nature,  as  secondary  causes,  have  each  their  respective 
influence  in  passing  off  rapidly,  or  in  passing  off  slowly  through 
springs,  the  waters  falling  upon  them.  The  depth  of  rain-fall 
varies  greatly  in  different  hydrographical  districts,  so  that  two 
rivers  with  the  same  extent  of  rain-basin,  may  differ  largely 
in  the  amount  of  their  maximum  volume.  Rain-shed  is  greater 
in  mountainous  districts  than  in  plains.  It  is  greater  in  equa- 
torial than  in  polar  regions,  and  varies,  even  in  the  same 
latitudes,  to  an  extent  often  as  great  as  that  between  Northern 
and  Southern  districts  ;  for  instance,  it  is  greater  in  Ireland 
than  in  Russia,  and  it  is  greater  on  the  Western  slopes  of  the 
Cascade  and  Rocky  mountains,  than  on  their  Eastern  slopes. 
The  sudden  melting  of  snow,  or  a  continued  rain-storm,  will 
sometimes  congregate  rapidly  into  a  river  channel  an  amount 
of  water  equal  to  a  high  multiple  of  its  average  outflow.  At 
Marseilles,  France,  in  a  shower  of  rain  of  14  hours  duration, 
thirteen  inches  have  fallen,  constituting  a  high  proportion  of 
its  rain-fall  for  twelve  months  ;  and  at  London,  England,  six 
inches  have  been  known  to  fall  in  one  and  a  half  hours — nearly 
one-fourth  its  mean  annual  fall.  And  from  the  same  cause, 
Western  rivers  are  seen  occasionally  to  rise  from  15  to  20  feet 
in  24  hours  ;  and  even  a  height  of  five  feet,  like  a  wall,  is  some- 
times observed  to  come  rolling  down,  sweeping  all  before  it  in 
the  descent.  There  are  various  causes  in  the  river-bed,  acting 
to  retard  the  flow  of  those  waters,  and  helping  by  that  retarda- 
tion to  raise  their  surface,  such  as  friction,  eddies,  sinuosities, 
and  other  circumstances.  M.  Yenturi  deduces  from  his 
experiments  on  tubes  with  enlarged  parts,  "  That  eddies 


26  PRINCIPLES   AND    PRACTICE   OP 

destroy  part  of  the  moving  force  of  the  current  of  the  River, 
of  which  the  course  is  permanent,  and  the  sections  of  the  bed 
unequal,  the  water  continues  more  elevated  than  it  would  have 
done,  if  the  whole  river  had  been  equally  contracted  to  the 
dimensions  of  its  smallest  section,  a  consequence  extremely 
important  in  the  theory  of  rivers,  as  the  -retardation  experi- 
enced by  the  water  is  not  only  due  to  the  friction  over  the 
beds,  but  to  the  eddies  produced  from  the  irregularities  in  the 
bed  and  the  flexures  and  windings  of  its  course,  a  part  of  the 
current  is  thus  employed  to  restore  an  equilibrium  of  motion 
which  the  current  itself  continually  deranges."  The  irregu- 
larities of  river-beds,  and  the  irregularities  of  rain-falls  are  thus 
seen  to  be  combined  in  producing  the  phenomena  of  floods. 
The  irregularities  of  rain-fall  are  of  course  causes  beyond 
human  influence,  but  the  co-operating  cause  of  floods — the 
peculiarities  of  river  channels — are  within  the  field  of  human 
operation,  and  become,  therefore,  the  special  object  of  enquiry 
to  the  Engineer  engaged  in,  and  people  affected  by  permanent 
or  periodic  overflows. 

All  rivers  decrease  in  their  rate  of  descent  as  they  approach 
the  outfall ;  and  this  decrease  is  made  over  a  series  of  curves 
gradually  flattening  until  they  flow  out  into  the  tangent  or 
horizontal  line  of  the  sea-level.  Short  water-courses  and 
minor  river-basins  in  mountainous  districts  are  generally  of  a 
precipitous  character.  Such  are  those  of  the  Alps,  and  of  the 
Western  slopes  of  the  Rocky  mountains.  The  large  rivers 
with  which  this  continent  abounds  are  generally  for  the  greater 
part  of  their  length  of  slow  descent.  The  average  fall  of  the 
Mississippi  river  for  the  whole  distance  from  the  gulf  of  Mexico 
to  the  confluence  of  the  Ohio,  following  the  windings  of  the 
river  during  low  water,  averages  very  nearly  three  inches  per 
mile.  Supposing  the  channel  of  the  river  straight  and  the 
rate  of  descent  uniform  between  those  points,  the  fall  would 
be  about  six  inches  per  mile.  But  the  actual  rate  of  declivity 


EMBANKING  LANDS  FROM  RIYER-FLOODS.  27 

in  a  river  is  considerably  increased  in  times  of  flood.  Thus, 
the  Nile  falling  into  a  tideless  sea,  rises,  at  the  city  of  Cairo 
during  floods,  25  feet,  at  Thebes,  36  feet,  and  at  the  first  cat- 
aract— a  point  nearly  equally  distant  from  the  mouth  as  Cairo 
from  the  Balize — about  40  feet.  The  Mississippi  river  falling 
into  a  sea  too  of  a  very  nearly  constant  elevation — rises  at 
New  Orleans  12  feet,  at  Friar's  Point,  Mississippi,  42J  feet,  and 
at  Cairo,  Illinois,  about  50  feet.  This  flood-rise  at  Cairo,  added 
to  the  elevation  of  low  water  at  that  point,  gives  an  average 
rate  of  fall  for  high  water,  following  the  windings  of  the  river, 
of  three  and  a  half  inches,  and  on  a  direct  line,  of  seven  inches 
per  mile.  There  is,  therefore,  in  the  circuitous  and  in  the 
rectilinear  distances  a  difference  of  fall  equal  to  half  an  inch 
and  to  one  inch  respectively  per  mile,  due  to  the  average  rate 
of  fall  during  high  water  at  Cairo,  over  and  above  that  due  to 
the  average  rate  of  fall  from  the  same  point  during  low  water. 
A  fixed  expression  has  been  deduced  for  the  velocity  of  small 
conduits.  No  formula  for  the  purpose  is  yet  found,  nor  is  one 
likely  ever  to  be  found,  applicable  to  the  infinitely  varying 
conditions  of  velocity  in  large  rivers.  Whatever  may  be  the 
co-efficients  and  the  combinations  necessary  to  give  precise- 
ness  to  any  mathematical  expression  for  river-flow,  the  terms 
of  that  expression  may  be  held,  in  general,  to  be  the  rate  of 
fall,  the  depth  of  volume,  and  the  content  of  the  sectional  area 
or  friction-surface  of  the  bed.  Any  change  in  either  of  those 
three  conditions,  will — all  things  else  being  equal — involve  a 
change  in  the  velocity  of  a  river.  Gravity  being  the  motor  in 
all  cases  of  water-flow,  that  flow  would,  unless  under  the  influ- 
ence of  some  retarding  cause,  take  place,  like  the  free  fall  of 
any  other  body,  with  a  constantly  operating  acceleration. 
These  retarding  causes  are  more  than  one  in  the  case  of  river- 
flow  ;  they  are  represented  by  the  loss  of  mechanical  effect 
arising  from  the  shocks  of  the  bank,  and  the  friction  of  the 
bed.  The  retardation  arising  from  friction  is  one  of  constant 


28  PRINCIPLES  AND  PRACTICE  OP 

operation.  The  lower  planes  of  the  cross-section  of  river-flow 
suffer  more  active  retardation  from  this  cause  than  the  upper 
planes  ;  the  former  being  retarded  by  the  friction  of  their 
motion  over  the  roughness  of  the  bed,  while  the  latter  are 
retarded  by  the  greatly  reduced  friction  of  sliding  over  the 
comparative  smoothness  of  the  lower  water-planes.  The  deeper 
the  volume  of  a  river,  the  higher  therefore,  is,  not  only  its 
surface  velocity,  but  also,  its  mean  velocity.  And  the  same 
remarks  apply  to  the  vertical  planes  of  the  volume  ;  the  great- 
est retardation  taking  place  at  the  sides,  the  least  in  the  centre 
of  the  stream.  The  greater  the  width,  therefore,  the  more 
active — so  far  as  side-friction  can  effect  the  result — is  the  flow. 
But  the  friction  of  the  sides  is  so  small  as  compared  with  that 
of  the  width,  that  the  latter  general  deduction  may  be  disre- 
garded ;  and  we  may  conclude,  practically,  that  an  active 
increase  in  the  velocity  of  a  stream — a  decided  diminution  in 
the  retardation  of  friction — is  always  the  result  of  an  increase 
of  depth. 

In  even  small  streams  a  fall  of  one-tenth  of  an  inch  per  mile 
will  produce  a  sensible  flow.  In  large  streams  this  rate  of 
inclination,  would,  as  seen  by  the  above  reasoning,  result  in  a 
current  proportionally  more  considerable.  The  frictional 
resistance  of  a  river-bed  is  higher  for  higher  velocities  than 
for  lower  ;  varying,  according  to  the  observations  and  deduc- 
tions of  M.  Eytelwein,  as  the  rate  of  the  square  of  the  velocity. 
Such  are  the  general  facts  of.  fall  and  friction. 

The  effects  of  tributary  waters,  on  the  volume  and  velocity 
of  streams,  appear  somewhat  paradoxical.  Genn^tte,  supported 
by  M.  Eytelwein,  asserts  that  one  river  may  absorb  another  of 
equal  magnitude  with  itself,  without  producing  a  sensible 
elevation  of  its  surface.  Cressy,  in  his  Encyclopedia  of  Civil 
Engineering,  sustains  this  opinion  by  citing  the  absorption  of 
the  Inn,  by  the  Danube  ;  of  the  Mayne,  by  the  Rhine  ;  of  the 
Sechio,  by  the  Po,  and  of  the  Teverone,  by  the  Tiber  ;  this 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  29 

absorption,  he  states,  taking  place  without  making  the  volume 
of  the  absorber  in  each  case  either  deeper  or  wider.  The  only 
effect  of  the  accession  to  the  body  of  water  passing  through 
the  main  channel,  in  each  .  of  the  instances  named,  is  said  by 
Cressy,  to  be  an  increase  in  the  velocity.  Guglielmini,  in 
evidence  of  the  same  opinion,  refers  to  the  accession  of  the 
waters  of  the  Ferrara,  and  Panaro,  branches  of  the  Po,  to  the 
volume  of  that  river  without,  as  he  alleges,  producing  any 
sensible  augmentation  of  its  channel. 

A  corresponding  increase  of  velocity  must  of  course  be 
supposed  a  consequence  of  such  an  accession,  if  we  are  to  accept 
as  a  fact,  that  the  accession  of  a  tributary  has  no  effect  on  the 
width  or  the  depth  of  its  main  out-fall.  This  increase  of  velocity 
in  the  united  volumes  must,  however,  be  referable  to  some  com- 
mensurate mechanical  cause.  The  tributary  volume,  it  is  true, 
discharges  into  the  united  volumes,  the  velocity  proper  to 
itself ;  and  therefore,  waiving  the  fact  of  altered  rate  of  fall, 
or  of  altered  depth  of  flow,  tKe  united  volumes  may  be  held,  on 
mechanical  grounds,  to  flow,  after  union,  at  a  proportional 
average  of  their  respective  velocities.  That  the  union  of  the 
two  waters  flows  off  without  any  increase  in  the  original  volume 
of  the  main  stream,  were  to  suppose  the  result  of  their  blend- 
ing of  mechanical  effect,  the  sum,  volume  for  volume,  of  their 
original  rates  of  flow.  If  the  two  volumes  were,  for  example, 
equal,  the  one  moving  originally  at  two  miles  an  hour,  the  other 
at  three  miles,  then  would  the  discharge  of  the  united  volumes, 
without  increase  of  width,  or  depth,  or  rate  of  descent,  suppose 
the  resulting  velocity  to  be  Jive  miles  an  hour.  Mechanically 
this  is  not  supposable.  Therefore,  must  we  come  to  the 
conclusion  that  it  is  impossible  that  the  union  of  two  rivers 
can  take  place  without  an  increase  after  the  union,  in  either 
width  or  depth.  Eytelwein  and  Cressy  must  clearly  have 
either  mistaken  the  fact  or  have  stated  it  erroneously. 

The  conclusions  of  the  respectable  names  given  under  this 


30  PRINCIPLES  AND  PRACTICE  OP 

head,  are,  like  all  conclusions,  open  to  question.  The  facts, 
however,  must  be  received  beyond  all  doubt.  While  there  can 
be  no  question  as  to  the  facts,  that  the  Danube,  the  Rhine,  the 
Po,  the  Tiber,  in  all  the  instances  of  accession  named,  have  not 
been  widened  or  devated  ;  the  inference  is  irresistible,  that  in 
all  these  instances,  they  must  have  been,  to  at  least  some 
extent,  deepened.  The  fact  of  deepening,  resulting,  as  pre- 
mised above,  in  a  proportional  diminution  of  frictional 
resistance  to  flow,  involves  directly  an  increase  in  the  rate  of 
flow.  This,  combined  with  the  mechanical  impulse  of  the 
tributary  volume,  must,  by  accelerating  the  velocity,  make  the 
increase  of  depth  proportionally  less  than  the  increase  of 
accession. 

It  has  been  remarked  by  several  writers  that  the  width  of 
the  Mississippi  below  the  junction  with  the  Ohio,  is  less  than  its 
width  above  the  junction.  This  is  not  only  true  of  the  river 
in  the  case  of  the  accession  of  the  Ohio,  but  also,  of  all  acces- 
sions below  that,  and  indeed,  of  the  channel  generally  from 
Cairo  to  the  Balize.  At  Cairo,  the  Mississippi  is  upwards  of 
a  mile  wide  ;  at  New  Orleans,  the  width  is  but  half  a  mile. 
But  this  narrowing  down-stream  is  accompanied  by  a  corres- 
ponding deepening — a  truth  that  is  established  popularly  by 
the  fact  that  the  higher  a  steam-boat  goes  up  stream,  in  low 
water,  the  more  difficult  is  the  navigation  ;  until,  at  Cairo, 
further  navigation  at  such  times  becomes  almost  impossible, 
even  for  the  smallest  craft. 

A  rough  approximation  of  the  sectional  areas,  in  times  of 
flood,  of  the  Mississippi,  at  Cairo,  and  at  New  Orleans,  in  con- 
junction with  a  like  statement  of  all  its  intermediate  tributary 
streams,  will  be  found  on  the  next  page. 

An  accession  of  some  500,000  square  feet  of  tributaries  is  seen, 
by  this  statement,  to  be  passed  through  the  Mississippi  river  at 
New  Orleans  with  an  increase  of  volume  over  that  at  Cairo,  of 
but  160,000  square  feet ;  and  through  a  channel  upwards  of 
twi—  *-  -  n  "  d  but  one-half  the  width. 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  31 

At  Cairo,  the  sectional  area  of  the  Mississippi,  is  about,  -     325,000  feet. 

Of  the  Ohio,  at  junction,  the  sectional  area  is  about,  -  260,000  feet. 

Of  the  St.  Francis,  at  junction,            do.        -        -  21,000  feet. 

Of  White  River,  at          do.                  do.     -        -  -    28,000  feet. 

Of  Arkansas,  at               do.                  do.        -        -  56,000  feet. 

Of  Yazoo,  at                    do.                 do.     -        -  -    21,000  feet. 

Of  Big  Black,  at             do.                 do.        -  21,000  feet. 

Of  Red  River,  at             do.                 do.    -        -  -    52,000  feet. 

Of  other  tributaries,  at    do.                  do.        -        -  18,000  feet. 


Total,     -        -    802,000  feet. 
Of  the  Mississippi,  at  New  Orleans,    -  480,000  feet. 

This  fact,  ascertained  loosely  as  it  is,  establishes  the  correctness 
of  the  general  conclusion  reasoned  to  above,  namely,  that 
while  on  the  authority  of  the  statements  of  Gennette,  Eytel- 
wein,  Guglielmini,  Cressy,  we  must  accept  the  fact  that 
tributary  accessions  to  the  volume  of  a  river  do  not  widen,  or 
elevate  their  general  level,  all  such  accessions  result  in  an 
accelerated  velocity,  and  an  increased  depth.  As  a  practical 
application  of  this  conclusion  in  the  case  of  the  Mississippi  river, 
it  may  be,  therefore,  safely  affirmed,  that  the  retention  of 
flood-water  in  the  channel  by  levees,  like  all  tributary  acces- 
sions to  its  volume,  while  deepening  the  channel,  and 
increasing  the  velocity  will  not,  as  a  direct  consequence, 
elevate  the  surface  of  the  water. 

The  conclusion  arrived  at  in  the  foregoing  paragraph  appears 
on  its  face  paradoxical.  Paradoxical  or  not,  it  must  be 
observed  that  it  is  a  conclusion  drawn  fairly,  from  undoubted 
premises.  It  will  be  said,  if  the  enclosure  of  swr/ace-flood-water 
within  the  channel  do  not  elevate  the  level  of  the  river-flow, 
how  is  it  that  the  accession  of  any  flood-water  at  all  produces 
that  elevation  ?  The  inference  drawn  above  is  not  affected  by 
this  question  ;  because,  not  declaring  that  there  are  no  varia- 
tions of  river-level,  it  applies  to  only  those  circumstances 
under  which  a  tributary-flood  is  discharged  into  the  river-chan- 
nel at  the  period  of  a  correspohding  flood  in  that  main  channel. 


32  PRINCIPLES  AND   PRACTICE   OF 

from  its  own  supplies.  The  conclusion  arrived  at  is  in  truth 
this  : — a  glut  of  water  in  the  Mississippi  will  not  be  increased 
in  level  by  the  accession  of  other  gluts,  from  the  Ohio,  Arkan- 
sas, <fec.  But  if  we  are  to  suppose  every  accession  of  flood- 
water  an  accession  of  height ;  and  that  we  begin  with 
over-flows  of  even  6  feet  at  the  accession  of  the  Missouri,  of 
6  feet  additional  at  the  accession  of  the  Ohio,  of  6  feet  more 
for  all  accessions  of  minor  streams,  of  6  feet  more  for  the 
accession  of  the  Arkansas,  of  6  feet  more  for  the  accession  of 
Red  Eiver,  the  flood  level  at  New  Orleans — assuming  no 
adaptation  of  channel  as  we  go  down-stream — would  be  30  feet 
above  the  surface  of  the  land  !  But  what,  on  the  contrary,  is 
the  fact  ?  The  elevation  of  floods  at  New  Orleans  is  alto- 
gether but  12  feet  above  the  low-water  mark,  which  increasing 
up-stream,  it  is  in  fact,  at  Cairo,  50  feet — and  this  in  the  face  of 
all  the  accessions  from  Hatchees,  St.  Francis,  White,  Arkansas, 
Yazoo,  and  Red  River. 

The  direct  agent  of  change  in  a  river-course  is  the  current. 
On  the  banks  this  acts  in  two  ways — by  friction,  and  by  impact. 
The  greater  the  velocity  the  greater  of  course  will  be  the 
length  of  the  rubbing  body  that,  moving  along  the  bed  and 
bank,  constitute  the  friction.  The  friction,  therefore,  varies 
with  the  velocity ;  being  twice  as  great  for  two  miles  as  for 
four  miles.  Friction,  varying  also,  as  the  weight  of  the 
rubbing  body  varies  as  the  depth,  being  twice  as  great  in  a 
depth  of  40  feet,  as  in  a  depth  of  20  feet.  All  sections  of 
channel  are  subject  to  this  consequence  of  flow  ;  but  the  more 
even  and  regular  the  section,  the  less  the  friction.  In  irregu- 
lar and  uneven  sections  the  friction  runs  from  friction  proper 
into  impact. 

Impact  begins  in  channels  where  friction  ends.  A  stream 
flowing  over  a  smooth,  straight  bed  is  resisted  by  only  the 
adhesion  due  to  friction  ;  but  over  a  rough,  crooked  bed  is 
resisted,  in  addition  to  this  adhesion,  by  shocks  to  the  regular- 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  33 

ity  of  its  flow,  whether  against  shoals,  bars,  stumps,  or  bends. 
This  further  resistance  combines  within  it  all  those  impedi- 
ments involving  impact ;  and  for  whatever  part  of  the 
cross-section  of  the  flow  is  engaged  in  this  impact,  varies  as 
the  weight  of  that  cross-section  multiplied  by  the  square  of  the 
velocity.  The  weight,  however,  varies  directly  as  the  depth, 
being  twice  as  great  for  a  depth  of  50  feet,  as  for  a  depth  of 
25  feet ;  and  hence  does  a  river  become  the  most  powerful 
agent  of  change  by  impact,  at  periods  of  highest  flood.  The 
velocity,  too,  increasing  with  the  depth,  shews  again  and  in  a 
higher  degree,  why  a  river  exerts  its  greatest  energy,  so  far  as 
impact  expresses  that  energy,  at  the  period  of  its  greatest 
depth.  For  impact  as  measured  by  velocity  increases  as  the 
square  of  the  velocity,  being  nine  times  as  great  for  the  same 
impediment  and  the  same  depth,  in  a  stream  of  six  miles  an 
hour,  as  in  a  stream  of  two  miles  an  hour. 

The  effects  on  river  beds  and  banks  from  friction  and  impact, 
cannot  be  given  here  more  satisfactorily  than  in  those  general 
elementary  terms.  No  experiments  that  have  come  under  my 
knowledge,  furnish  a  measure  of  the  effects  of  friction  and 
impact,  in  the  case  of  rivers,  by  practical  examples. 

Friction  and  impact,  so  far,  have  been  touched  on  as  agents 
for  excavating  material.  After  this  excavation,  however,  they 
continue  to  act  on  the  material  excavated  with  their  combined 
forces.  A  lump  of  earth  for  example,  being  rubbed  off  by 
friction  or  knocked  off  by  impact  in  the  channel,  is  taken  up  by 
the  water  and  impelled  forward  by  the  rubbing  and  the  striking 
of  the  flow.  Small  bodies,  and  bodies  of  a  weight  a  little  more 
than  water,  are  thus  moved  along  by  the  stream  in  suspension  ; 
larger  bodies  of  a  weight  considerably  greater  than  water, 
being,  by  the  same  power,  rolled  forward  over  the  bottom. 
This  energy,  this  power  of  transportation  of  material  within  its 
channel  by  a  river,  may  be  understood  in  relative  terms  by  the 

remark  that  it  is  the  combined  effort  of  friction  and  impact — of 

3 


34  PRINCIPLES   AND    PRACTICE   OF 

the  rubbing  of  the  planes  of  water  that  flow  past  that  material 
and  of  the  striking  of  that  part  of  the  flow  which  it  impedes. 
Practical  results,  however,  give  this  energy  a  plainer  expression. 
The  following  facts,  ascertained  after  a  series  of  careful  experi- 
ments by  Dubuat,  show  clearly  the  absolute  energy  of  several 
velocities  of  rivers  for  the  transport  of  materials  loosened  by 
their  currents,  or  otherwise  deposited  in  their  beds  : — 

Clay  fit  for  pottery  removed  by  water  flowing  at  the  rate  per  second  of  3*  inches. 

Fine  sand  removed  by  water  flowing  at  the  rate  per  second  of  6J  inches. 
Gravel  about  the  size  of  peas  removed  by  water  running  at  the  rate  per 

second  of __7j  inches. 

Gravel  about  the  size  of  beans  removed  by  water  running  at  the  rate  per 

second  of  -     '   -        -        -  12|  inches. 

Shingle — large  gravel — about  one  inch  in  diameter,  removed  by  water 

running  at  the  rate  per  second  of        -        -        -        -        -        -  25£  inches. 

Flints  about  the  size  of  hen's  eggs  removed  by  water  running  at  the  rate 

per  second  of--- -40  inches. 

Broken  stones  removed  by  water  at  the  rate  per  second  of       -        -  48  inches. 

Soft  rocks  begin  to  yield  with  a  velocity  per  second  of        -        -        -  52  inches. 

Rocks  with  distinct  stratification  begin  to  yield  with  velocity  per  second  of  72  inches. 

Hard  compact  rock  begins  to  yield  with  a  velocity  per  second  of         -  120  inches. 

From  this  table  it  appears  that  the  very  moderate  velocity  of 
950  feet  per  hour,  is  capable  of  moving  clay  ;  of  1900  feet  per 
hour,  capable  of  moving  fine  sand,  and  of  half  a  mile  an  hour, 
capable  of  moving  coarse  gravel.  The  carrying  or  propelling 
power  of  a  stream  on  bodies  within  it,  is  seen  from  the  table  to 
increase  with  its  velocity  ;  the  materials  capable  of  movement 
in  a  current  of  4  miles  an  hour,  being  incapable  of  motion  at  3, 
2,  or  1  mile  an  hour.  This  fact  leads  to  some  of  the  most  im- 
portant changes  in  rivers  as  will  be  shown  below.  As  no  prac- 
tical examples  of  the  abrasive  effects  of  a  current  have  been 
given  above,  it  may  be  observed  here,  that  those  effects,  result- 
ing as  they  do  from  the  same  causes,  which,  certainly  with  an 
energy  less  in  degree,  constitute  the  propelling  power  of  cur- 
rents, are  presented  in  the  facts  of  the  above  table  relatively. 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  35 

Impact  and  friction  "  washing  away  "  or  "  caving  in "  the 
material  of  a  river  channel,  it  has  been  seen  that  impact  and 
friction  continue  to  act  afterwards  on  the  material  so  "  washed  " 
or  "  caved,"  for  its  propulsion  along  the  channel  into  the  out- 
flow or  sea.  It  has  also  been  shown  that  this  propelling  power 
is  greater  or  less  as  the  velocity  of  the  stream  is  greater  or  less. 
Friction,  it  has  too  been  premised,  is  greatest  in  its  retardation 
of  flow  at  the  bottom  and  at  the  sides,  the  rate  of  flow  being 
always  greatest  in  the  middle,  and  at  the  top  of  the  stream,  and 
diminishing  from  that  top  and  from  that  middle  on  either  side, 
until,  at  the  bottom  and  at  the  sides,  it  becomes  the  least.  This 
consideration  may  be  put  in  this  shape  :  the  velocity  of  a  stream 
is  unequal  at  every  point  of  its  section.  Now  a  mass  of  material 
broken  off  or  rubbed  off  by  a  current  from  the  bed  or  bank  is, 
when  so  broken  or  rubbed  off,  placed  free  to  move  in  a  current 
of  a  certain  velocity.  This  velocity,  let  it  be  supposed,  has 
energy  sufficient  to  propel  that  mass.  Like  all  moving  bodies, 
the  motion  of  this  mass  tends  to  follow  a  straight  line  in  the 
direction  of  the  force  acting  on  it.  But  at  a  sudden  bend  or 
obstacle  in  the  river  the  thread  of  the  stream,  acting  on  this 
soft  mass,  may  be  supposed  to  be  deflected  at  a  large  angle 
with  its  original  deflection.  The  mass,  being  heavier  than  the 
corresponding  thread,  will  be  deflected  from  its  original  direction 
at  a  smaller  angle  than  the  water  ;  and  hence,  will  take  its 
place  in  a  different  part  of  the  water-section.  By  irregularities 
in  the  direction  of  the  flow  the  bodies  rolled  along  a  river  bed 
are  thus  seen  to  be  constantly  shifted  from  one  position  in  the 
cross  section  to  another  position  in  that  section ;  and  conse- 
quently are  seen  to  be  shifted  into  velocities  constantly  changing. 
Of  bodies  carried  along  by  a  stream  and  so  light  as  to  be  held 
at  first  in  suspension,  the  constant  action  of  gravity  tends  to 
the  depression  of  those  bodies  ;  and  thus,  in  urging  them  con- 
stantly downwards,  brings  them  in  their  dropping  through 
different  depths,  into  different  rates  of  flow.  All  material  then, 


36  PKINCIPLES  AND  PKACTICE  OF 

whether  large  or  small,  light  or  heavy,  are  seen  to  be  subject 
in  river  channels,  to  constantly  changing  velocities  j  and  hence, 
the  carrying  power  of  rivers  depending  on  velocity,  all  material 
too  heavy  or  too  large  to  be  moved  by  the  smaller  velocities  of 
the  cross-section  of  the  stream,  when  once  shifted  into  a  position 
having  any  of  those  smaller  velocities,  sinking  to  the  bottom, 
becomes  fixed.  The  lighter  and  smaller  bodies  rolling  along 
that  part  of  the  section  where  this  material  thus  becomes  fixed, 
accumulate  around  it  as  a  nucleus,  and  this  process  of  fixing 
heavier  matter  and  retaining  lighter  matter,  results  in  shoals, 
bars,  islands,  and  those  deposits  known  on  the  Mississippi,  as 
"  making  banks." 

The  amount  of  material  carried  down-stream  by  a  river, 
varies,  as  has  already  been  seen,  with  the  velocity  and  volume 
on  one  hand,  and  varies  on  the  other  hand,  with  the  hardness 
or  softness,  lightness  or  heaviness  of  the  material  composing 
the"  bed  and  bank.  The  quantity  of  solid  matter  borne  for- 
ward by  the  Ganges  is  estimated  at  1-40  of  its  volume,  the  total 
quantity  of  earth  propelled  per  year  by  that  river  being  esti- 
mated at  the  almost  incredible  amount  of  about  315,000  million 
cubic  yards.  The  Rhine  is  estimated  by  Mr.  Homer  to  propel 
solid  matter  to  the  amount  of  1-16000  of  its  volume.  At  New 
Orleans  the  earthy  matter  propelled  by  the  Mississippi  is  esti- 
mated by  Dr.  Riddell,  taking  a  mean  annual  average,  at  an 
amount  of  1-1700  of  the  volume  of  the  flow.  The  Mississippi 
is  shown  by  the  estimate  of  Sir  C.  Lyell  to  carry  earth  below 
New  Orleans  to  the  amount  per  annum  of  137,000,000  cubic 
yards. 

Of  the  whole  material  propelled  by  a  stream,  a  proportion 
has  been  seen  to  be  precipitated  from  mechanical  causes  in  the 
form  of  shoals,  bars,  islands,  "making  banks,"  &c.  The  residue, 
however,  of  this  quantity  of  matter  is  carried  forward  to  the 
debouch  ;  and  pushed  for  further  propulsion  into  the  outfall 
stream,  or  partly  for  further  removal,  partly  for  permanent  de- 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  37 

posit — impelled  into  the  sea.  This  deposit  of  material  by  sea- 
discharging  rivers,  is  the  cause  of  that  general  accompaniment 
of  a  system  of  rivers— the  Delta.  Constant  in  its  operation, 
this  canse  of  the  formation  of  Deltas  would,  under  circum- 
stances always  the  same,  lead  to  the  constant  extension  of  those 
Deltas.  This  extension,  however,  must  be  held  under  its  gen- 
eral circumstances  to  take  place,  as  measured  by  its  direct  ad- 
vance, at  a  rate  constantly  diminishing,  until  finally  it  shall 
have  reached  its  limit  of  direct  advance.  The  trend  of  a 
shore-line  may,  for  instance,  be  supposed  to  place  the  debouch 
of  a  river  in  dead  water  ;  and  this  dead  water,  favoring  the 
precipitation  of  material,  the  earth  propelled  into  it  by  the 
river,  produces,  to  a  certain  point,  a  constant  direct  advance  of 
that  river's  Delta.  At  this  certain  point,  however,  the  Delta 
may  be  supposed  to  have  passed  from  the  dead  water  of  its 
original  formation,  and  to  have  become  subject  to  the  disturb- 
ing influence  of  an  active  current.  Direct  advance  at  this 
stage  of  its  growth  may  be  thus  considered  at  an  end.  The 
direction  of  the  river-flow  crossing  the  course  of  the  sea-cur- 
rent at  an  angle,  the  resulting  direction  of  commingling  and  of 
deposit,  follows  a  bend  increasing  more  or  less  rapidly,  accord- 
ing to  the  energy  of  the  sea-current,  as  compared  with  that  of 
the  river,  until,  finally,  it  shall  have  assumed  the  line  of  the 
sea-current.  Such,  in  general,  are  the  causes  and  condition  of 
the  growth  of  Deltas.  They  apply  alike  to  the  Deltas  of  the 
Mississippi  in  this  country  •  of  the  Orinoco  in  South  America  j 
of  the  Ganges,  of  the  Irrawaddy,  of  the  Indus,  <fcc.,  in  Asia  ; 
of  the  Nile,  and  of  the  Niger  in  Africa  ;  and  of  the  Rhine,  of 
the  Rhone,  of  the  Po,  of  the  Danube,  &c.,  in  Europe. 

The  rates  of  advance  in  Deltas,  consequent  as  they  are  on 
the  varying  causes  affecting  their  formation,  are  variable  for 
different  Deltas. 

The  Ganges  and  Burrumpooter,  deliver  into  the  Bay  of 
Bengal  solid  material  to  the  enormous  amount — during  the 


38  PRINCIPLES  AND   PRACTICE   OF 

flood  season — of  500  million  cubic  yards  every  twenty-four 
hours.  There  is  no  information  at  hand,  as  to  the  rate  of 
growth  of  the  Ganges-Burrumpooter  Delta.  The  incomplete- 
ness of  the  recorded  facts  of  the  rivers  of  the  great  Deltas  of 
the  world,  makes  it  impossible  to  deduce  any  general  law  an  to 
the  rate  of  Delta  growth  in  any  particular  case.  In  this  place 
may  be  added  all  that  are  at  hand  of  the  facts  of  Delta  growth  ; 
and,  indeed,  perhaps  this  may,  after  all,  be  quite  sufficient  for 
the  practical  purpose  aimed  at  under  this  particular  head. — 
The  Delta  of  the  Nile  has  advanced  but  two  miles  since  the 
time  of  Herodotus  ;  but  small  as  the  consequent  rate  of  advance 
is,  it  has  now  been  ascertained  to  have  altogether  ceased.  The 
Po,  and  the  Adige,  discharging  at  the  same  point  into  the 
Adriatic,  have  formed  their  joint-Delta  since  the  time  of  the 
birth  of  Our  Saviour.  One  hundred  miles  in  width,  this  Delta 
has,  up  to  the  present  time,  advanced  into  the  sea  upwards  of 
20  miles.  Sir  C.  Lyell,  after  comparing  the  present  tongue  of 
land  below  New  Orleans,  with  the  map  published  by  Charlevoix, 
alleges  that  the  Delta  of  the  Mississippi  River  has  not  advanced 
more  than  a  mile  in  a  century.  Mr.  Rogers,  in  his  report  to 
the  British  Association  on  the  Geology  of  North  America, 
says  however,  that,  "  as  an  example  of  the  rate  at  which  it  is 
growing,  the  old  Balize  erected  at  the  mouth  of  the  river,  about 
the  year  1724,  is  now  (1834)  two  miles  above  it.  There  waa 
not  at  that  time,  the  smallest  appearance  of  the  island  on 
which,  42  years  after,  Ulloa  caused  barracks  to  be  erected  for 
the  pilots,  and  which  is  now  known  as  the  new  Balize.  The 
distance  from  the  mouth  of  the  river  at  which  the  chief  deposit 
of  sediment  usually  takes  place  is  about  two  miles  ;  when 
these  shoals  accumulate  sufficiently  they  form  small  islands, 
which  soon  unite  and  reach  the  continent,  and  thus  the  Delta 


increases." 


In  this  statement  of  the  growth  of  Deltas  it  must  be  observed 
that  the  statement  for  that  of  the  Nile  and  of  the  Mississippi,  is 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  39 

applicable  to  rivers  unconfined  by  Levees.  The  Nile  overflows 
its  banks  without  artificial  restraint.  The  Mississippi,  up  to 
the  period  of  the  observations  referred  to,  had  been  but  very 
partially  Leveed  j  and  hence  do  those  observations  of  Mr.  Rogers 
refer  to  a  river  without  Levees.  The  facts  of  the  growth  of  the 
Delta  of  the  Po-Adige  are,  however,  since  the  sixteenth 
century,  those  of  a  Delta  formed  by  a  river  whose  floods  are 
confined  within  artificial  banks.  The  rate  of  advance  of  the 
Delta  of  the  Nile  from  the  birth  of  History  until  now,  has  been 
4  feet  a  year  ;  of  the  Mississippi  from  1724  to  1834  has  been 
96  feet  a  year ;  of  the  Po-Adige,  for  the  period  between  the 
beginning  of  the  first  and  the  beginning  of  the  thirteenth  cen- 
tury, 22  feet  a  year  ;  for  the  next  following  400  years  the 
advance  has  been  82  feet  a  year  ;  and  for  the  200  years  next 
after  that,  it  has  advanced  at  the  rate  of  229J  feet.  The  present 
Levee  system  of  the  Po  had  its  origin  in  the  13th  century,  but 
was  incomplete  until  the  commencement  of  the  17th  century. 
Since  the  beginning  of  the  17th  century,  however,  the  em- 
bankments of  the  Po  and  Adige  have  been  completed  from  end 
to  end.  The  unleveed  period  of  the  Po  shows  an  annual  rate 
of  advance  in  its  Delta  of  22  feet.  But  from  the  introduction 
of  the  Levee-system  on  that  river  (taking  the  average  during 
the  whole  period  of  its  progress.)  the  rate  of  advance  of  the  Po- 
Adige  Delta  ran  up  from  22  feet  annually  to  82  feet :  and  from 
the  completion  of  the  Levee-system,  taking  the  experience  of 
200  years,  the  advance  of  the  Po-Adige  Delta  has  run  up  from 
82  feet  annually  to  a  yearly  rate  of  229 1  feet.  The  conclusion 
then  from  the  experience  in  the  case  of  the  Po  is  irresistible, 
in  the  absence  of  any  other  especial  cause,  to  account  for  such 
an  accelerated  advance,  that  the  confinement  of  the  river  Po 
within  embankments  has  caused  its  Delta  to  advance  into  the 
sea  with  comparative  rapidity.  Levees  therefore,  may  be  held 
to  involve  an  accelerated  rate  of  extension  of  a  river-Delta. 
The  advance  of  its  Delta  exerts  decided  influence  on  the  high- 


40  PRINCIPLES  AND   PEACTICE  OF 

water  level  of  a  river.  The  flood-height  of  the  Mississippi,  which 
at  New-Orleans  has  been  stated  already  at  12  feet  above  low- 
water,  is  at  Friar's  Point  42 J  feet  above  low  water,  and  at  Cairo 
is  50  feet.  Every  3  inches  of  elevation  at  New  Orleans  repre- 
sents therefore  an  elevation  at  Cairo  of  12|  inches.  Now  the 
rate  of  fall  from  New  Orleans  to  the  sea  is  about  1J  inches  per 
mile,  and  therefore  an  advance  of  the  Mississippi  Delta  at  an 
accelerated  rate  based  on  the  acceleration  resulting  from  Levees 
to  the  advance  of  the  Po-Adige  Delta  would  give — by  an  exten- 
sion in  100  years  of  4|  miles  of  Delta — an  additional  elevation 
of  6J  inches  to  flood  level  at  New  Orleans,  an  additional  eleva- 
tion to  that  level  at  Friar's  Point,  of  23  inches,  and  at  Cairo  an 
additional  elevation  of  27  inches.  The  relative  height  of  high 
water  at  any  point  on  the  Lower  Po,  in  comparison  with  that 
at  any  point  on  the  Upper  Po,  is  not  conveniently  obtainable  ; 
but  assuming  it  the  same  as  between  that  at  New  Orleans,  and 
that  at  the  Balize  on  the  Mississippi,  the  extension  of  the  Po- 
Adige  Delta  since  the  completion  of  the  Po  and  Adige  Levees— 
9  miles  of  extension— must  have  occasioned,  for  the  preservation 
of  the  same  rate  of  incline  of  outflow  from  Ferrara  down 
stream,  as  from  New  Orleans  down  stream,  an  elevation  at 
Ferrara  of  13  inches.  The  elevation  of  the  Po,  however,  at 
Ferrara  is  measured  not  by  inches  but  by  feet ;  and  the  increase 
of  this  elevation  since  the  completion  of  the  Levees  must,  there- 
fore, be  referred  to  some  other  direct  cause  than  the  extraor- 
dinary extension  of  the  Delta. 

The  overflow  of  a  river  discharges  a  large  proportion  of  its 
earthy  matter  upon  the  land.  The  confinement  of  the  River 
within  Levees  confines  this  proportion  of  its  earthy  matter  to 
the  channel.  The  immense  amount  of  the  material  so  added 
to  the  work  of  the  stream,  may  be  inferred  generally  from  the 
fact  that  in  the  case  of  the  Nile,  it  was  distributed  over  Egypt 
by  overflow,  and  has  caused  the  elevation  of  the  whole  surface 
of  the  country  since  the  Christian  era,  at  an  average  rate  per 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  41 

hundred  years  of  4J  inches.  The  greatness  of  the  aggregate 
mass  of  matter  added  to  the  original  proportion  in  its  volume 
by  the  construction  of  Levees,  may  be  inferred  generally,  by 
the  immense  additions  resulting  from  Levees  to  the  growth  of 
Deltas.  But  the  carrying  power  of  a  water-course,  like  all 
other  mechanical  agencies,  has  its  limit ;  and  when  we  see  any 
cause  loading  it  beyond  its  previously  established  energy,  we 
may  reasonably  expect  that  a  portion  of  its  excessive  work 
will  of  necessity  be  left  undone.  The  motive  power  of  a  river 
acting  up  to  its  limit  in  the  removal  of  matter  from  its  source 
to  the  sea,  may  be  readily  supposed  under  its  insufficiency  for 
the  removal  of  the  extra  matter  accumulated  within  its  Levees 
to  drop  a  portion  of  that  matter  into  irregularities  in  its  bed. 
The  matter  so  dropped  may  be  supposed  to  accumulate  in 
layers,  as  every  accession  of  material  increases  the  weight  of 
matter  to  be  moved,  over  and  above  the  enorgy  of  the  stream. 
But  these  causes  of  deposit  in  the  beds  of  rivers  apply  in  the 
surcharging  of  matter  in  streams  whether  Leveed  or  unleveed, 
though  from  the  retention  of  all  the  matter  within  the  channel 
by  Levees,  much  more  strikingly  in  the  case  of  Levees.  The 
Nile  illustrates  the  fact  that  unleveed  rivers  undergo  a  constant 
elevation  of  their  beds  ;  for  while  the  matter  deposited  during 
the  overflows  of  that  stream  as  already  stated,  has  elevated  the 
surface  of  Egypt  4J  inches  per  century,  the  matter  deposited 
within  the  bed  of  the  river  has  elevated  the  level  of  that  bed 
at  the  same  rate.  The  facts  in  this  case  are  so  well  defined 
that  it  may  be  well  to  place  them  here  on  record.  At  Dami- 
etta,  the  Balize  of  the  Nile,  where  the  elevation  of  overflow 
in  the  river  is  imperceptible,  the  elevation  in  the  level  of  the 
river-bed  and  river-bank  is  inappreciable.  At  Cairo,  120  miles 
from  the  mouth,  where  the  flood-level  is  25  feet  above  low 
water-mark,  the  elevation  of  the  land  and  of  the  river-bed  is, 
since  the  Christian  era,  5  feet  10  inches.  At  Thebes,  £JOO 
miles  from  the  mouth,  where  the  flood-level  is  36  feet  above 


42  PRINCIPLES  AND   PRACTICE   OP 

the  low  water  line,  the  land  and  the  river-bed  have  been 
elevated,  since  the  birth  of  Our  Saviour,  7  feet ;  while  at  the 
first  Cataract,  100  miles  higher  up-stream,  the  level  of  the  bed 
and  of  the  bank  have  been  raised,  since  the  same  period,  as 
much  as  9  feet.  Assuming  the  same  width  of  channel  in  the 
Nile  at  Cairo,  at  Thebes,  and  at  the  first  Cataract,  and 
assuming  further  the  same  amount  of  detritus  carried  off,  vol- 
ume for  volume,  by  the  overflow  at  each  of  those  three  places, 
we  may  not  be  surprised  to  find  that  a  40  foot  flood,  giving  an 
elevation  of  bed  to  the  extent  of  9  feet,  a  36  foot  flood  an 
elevation  of  bed  to  the  extent  of  7  feet,  and  a  25  foot  flood  an 
elevation  of  bed  to  the  extent  of  5  feet  10  inches,  the  height 
of  flood  bears  an  almost  uniform  proportion  to  the  height  of 
the  elevation  of  the  bed.  Where  the  height  of  flood  is  nothing 
the  elevation  of  bed  is  also  nothing — at  Damietta.  In  1800 
years,  it  is  thus  seen,  that  for  every  foot  high  of  the  flood  at 
Cairo,  the  Nile  has  elevated  its  bed  2.80  inches,  at  Thebes  2.34 
inches,  and  at  the  first  Cataract  has  elevated  its  bed  for  every 
foot  of  flood,  2.70  inches.  This  furnishes  for  streams  perfectly 
analagous  in  all  particulars  to  the  Nile,  an  approximate  scale  for 
estimating  the  rate  at  which  they  elevate  their  beds  while  un- 
disturbed by  Levees  in  the  distribution  of  their  detrital  matter 
over  the  adjacent  countries.  But  while  such  is  the  rate  of  bed 
elevation  in  unleveed  streams,  we  have  seen,  as  reasoned  to 
above,  that  the  rate  of  bed  elevation  must  necessarily  be  much 
more  rapid  in  rivers  confined  by  Levees.  But  one  special  fact 
confirmatory  of  this  general  proposition  is,  however,  within 
our  reach.  The  Rhine,  which  is  Leveed  from  the  sea  almost  to 
its  source,  has  since  the  Christian  era  elevated  its  bed  at  the 
City  of  Mayance,  13  feet  4  inches.  The  Levee  influence  in 
this  case  has  been  in  operation  for  but  300  years  ;  and,  there- 
fore, assuming  the  rate  of  elevation  in  the  river  when  it  over- 
flowed its  banks  the  same  as  that  of  the  average  of  the  Nile, 
the  bed-elevation  for  the  1500  years  of  overflow  must  have 


EMBANKING   LANDS  FROM   RIVER-FLOODS.  43 

been  6  feet,  and  for  the  300  years  of  Levees  be  so  much  as  7 
feet  4  inches,  or  six-fold  as  great.  The  flood-level  of  the  river 
Po,  it  is  true,  is  said  to  be  higher  than  the  roofs  of  the  houses 
in  the  city  of  Ferrara  ;~but  this  statement  is  so  loose  that  it 
may  mean  very  much  or  very  little.  If  the  houses  referred  to 
be  but  one  story  high,  the  flood-level  described  in  the  statement 
may  not  be  higher  above  the  streets  than  ten  or  twelve  feet. 
In  London  to-day,  it  would  not  be  considered  wonderful  if  we 
heard  that  the  Thames,  during  high  tides,  stood  as  high  as 
the  eaves  of  some  of  the  small  houses  in  Blackwall,  south  of  the 
Thames.  And  in  New  Orleans  it  would  not  be  at  all  surprising 
to  learn,  that  during  the  late  floods,  the  water  of  the  Missis- 
sippi stood  higher  than  the  roofs  of  some  of  the  little  squat 
cottages  on  the  edge  of  the  swamp  sloping  toward  Lake  Pon- 
chertrain.  Originally,  marine  swamps,  as  London,  New  Orleans 
and  Ferrara,  had  been,  it  is  after  all  not  so  very  remarkable 
that  the  levels  of  those  swamps  should  be  found  now,  as  they 
doubtless  have  been  from  time  immemorial,  considerably 
depressed  below  flood-water.  Seeing  then  that  the  record  is  so 
loose  in  the  case  of  the  Po,  it  may  be  assumed  that  while  that 
record  points  to  a  great  elevation  in  the  river-surface  since  the 
construction  of  its  Levees,  such  an  elevation,  from  the  manner 
in  which  it  is  stated,  must  not  of  necessity  be  held  as  by  any 
means  alarming.  So  much  for  the  reasoning  and  the  facts  as 
to  the  elevation  of  river-levels,  whether  the  rivers  be  or  be 
not  confined  by  Levees.  This  question  of  bed-elevation  and, 
therefore,  of  surface-elevation,  has  been  made  a  great  bugbear 
in  reference  to  the  embankments  along  the  Mississippi  ;  but 
when  the  few  facts  known  in  the  case  are  subjected  to  exami- 
nation, only  such  planters  as  take  a  very  active  interest  in  their 
great  grandchildren  will,  while  reclaiming  the  magnificent 
wastes  of  the  Mississippi,  trouble  themselves  by  the  reflection 
that  after  the  reclamation  of  those  lands,  they  may  revert  in 
some  future  century  back  to  swamp,  on  the  ground  that  the 


44  PRINCIPLES  AND   PRACTICE   OF 

works  of  reclamation  tend  to  elevate  the  flood-level  of  the 
river,  according  to  the  experience  of  a  city  300  miles  up  the 
Rhine,  at  the  rate  per  year  of  less  than  one-third  of  an  inch ! 

Incidental  to  the  question  of  Levees,  a  few  remarks  may  be 
added  on  the  subject  of  Debouch-bars.  In  a  Delta  these  bars 
mark  the  shallowest  water  of  its  respective  passes  ;  the  volume 
deepening  up-stream  until,  at  the  junction  of  the  passes,  it 
reaches  its  general  depth.  The  Rhone,  at  Aries — 20  miles 
from  the  sea — has  a  depth  of  43  feet,  whereas  the  depth  of 
water  on  its  bar  is  but  6  feet  6  inches.  This  river  has  five 
passes  or  mouths.  The  Po  di  Yolano — one  of  the  passes  of  the 
River  Po — has  a  depth  on  the  bar  of  but  2  feet  6  inches  •  while 
some  seven  miles  up-stream,  that  depth  increases  to  ten  feet. 
The  same  general  fact  has  been  observed  at  all  the  seven  passes 
of  the  Nile,  and  of  the  numerous  passes  of  the  Ganges.  This 
law  of  Delta-debouch  is  illustrated  forcibly  in  the  case  of  the 
Mississippi.  The  South-west  pass — the  deepest  of  the  whole, 
has,  according  to  the  United  States  Coast  Surveys  of  1851  and 
'52,  a  depth  of  about  13  feet,  whereas,  according  to  Sir  C. 
Lyell,  the  river  has  a  depth  at  New  Orleans  of  168  feet. 

In  Deltas,  rivers  always  divide  into  branches.  Consequent 
on  this  branching  the  loss  of  volume  in  each  outlet  results — 
by  the  great  increase  of  friction,  &c. — in  a  loss  of  momentum. 
This  loss  of  momentum,  lowering  the  aggregate  carrying- 
power  of  the  stream,  results  in  a  proportional  acceleration  of 
deposit ;  and  therefore,  going  on  from  its  starting  point — the 
branching — under  the  effects  of  a  constant  retardation,  reaches 
its  limit  on  the  pass-bar.  This,  then,  is  the  point  of  greatest 
deposit,  and  therefore  of  least  depth  ;  whereas,  the  branching 
point  is  the  point  of  least  deposit,  and  therefore,  of  greatest 
depth.  Thus  we  find  the  Rhone,  the  Po,  the  Nile,  the  Ganges, 
like  the  Mississippi,  all  shallow  in  their  passes,  and  deep  above 
the  separation  of  those  passes  from  the  main  channel.  These 
facts  and  reasonings  on  Delta-bars  point  directly  to  the  natural 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  45 

remedy  for  lowering  the  water-line  through  a  Delta  and  remov- 
ing its  bars.  The  diffusion  of  the  water-flow  being  the  cause 
of  those  evils,  their  remedy  lies  clearly  in  its  concentration. 
The  condensing  of  the  whole  volume  of  a  stream  in  one  channel 
will,  by  increasing  its  momentum,  give  a  carrying  power  that 
will  remove  and  transport  far  out  to  sea,  the  silt  that,  with  an 
inferior  carrying  power,  sinks  into  the  bed  of  half  a  dozen 
passes.  The  improvement  of  river-beds,  whether  for  the 
purposes  of  navigation  or  drainage,  ought  never  to  lose  sight 
of  the  prime  importance  of  concentrating  the  flow,  in  order  by 
thus  increasing  the  momentum — the  "  scouring"  power — of 
that  flow  to  remove  the  greatest  possible  amount  of  deposit 
from  the  bed,  and  thereby  deepen  the  channel  ;  to  propel  that 
deposit  out  into  the  distributing  currents  of  the  sea,  and 
thereby  retard  or  stop  altogether,  the  extension  of  the  Delta. 
This  conclusion  is  confirmed  by  the  experiments  of  Genn6tte, 
the  observations  of  Guglielmini,  and  all  the  subsequent  expe- 
rience of  the  most  respectable  practitioners  in  Hydraulic 
Engineering. 

The  bars  of  the  Mississippi  mouths  are  subjects  of  great  im- 
portance to  commerce.  The  report  of  attempts  to  remove  one 
or  more  of  those  bars  by  dredging,  is  incredible.  Such  an  effort 
were  a  repetition  of  the  story  of  removing  the  soil  of  the  Augean 
stable.  The  mechanical  power  engaged  in  piling  up  material 
across  the  passes  of  the  Mississippi  is  that  of  the  Mississippi 
itself;  and  it  were  the  rankest  of  folly  to  attempt  to  undo  the 
constant  work  of  that  power  by  the  puny  efforts  of  some  100- 
horse-power  dredge.  The  Mississippi  itself  is  the  only  power 
that  can  be  brought  to  bear  in  the  case  to  undo  permanently 
the  work  of  the  Mississippi.  The  Clyde,  a  century  ago,  did 
not  present  a  navigation-depth  of  over  three  feet  as  high  as  the 
City  of  Glasgow  ;  but,  though  the  bars  and  general  bed  were 
hard  gravel,  such  has  been  the  effect  of  concentrating  its  waters 
between  regular  lines  of  wharfs  and  jetties  that  it,  to-day,  bears  to 


46  PRINCIPLES  AND   PRACTICE  OP 

the  Quays  of  Glasgow  sea-going  vessels  of  some  20  feet  draught. 
Concentration  then  of  its  waters  in  one  channel  is  the  only 
means  for  removing  permanently  the  Mississippi  bars  j  and 
thereby  preserving  for  New  Orleans  a  commerce  that  otherwise 
must  become  every  day  more  embarrassed  as  the  Delta-advance 
adds  uncertainty,  difficulty,  and  danger  to  its  communication 
with  the  sea. 

But  the  commercial  ground  applies  also  to  the  other  grounds 
of  this  course.  The  concentration  of  the  waters  of  the  Mis- 
sissippi will  not  only  assist  shipment  by  removing  the  pass-bar, 
but  will  assist  drainage  by  keeping  down  the  water-line.  The 
greater  the  momentum  at  the  mouth,  the  greater  the  power  of 
the  river  in  displacing  sea-water,  and  the  greater  the  displace- 
ment of  sea-water,  the  greater  the  outflow  of  river-water. 
Thus  then  does  the  concentrating  of  the  stream  tend  to  the 
depression  of  the  up-stream  water-level.  But  the  elevation  of 
the  water-level  in  Delta-rivers  has  been  shown  above  to  go  on 
steadily  with  the  extension  of  the  Delta — a  mile  of  extension  in 
that  of  the  Mississippi  being  taken  to  represent  an  elevation  in 
the  flood-level  at  New  Orleans,  of  1J  inches,  at  Friar's  Point  of 
5J  inches,  and  of  6J  inches  at  Cairo.  While  the  increased  dis- 
placement of  sea-water,  as  suggested,  leads  to  a  proportional 
lowering  of  the  flood-level,  the  full  effect  of  that  lowering  will 
be  experienced  permanently  by  the  removal  of  that  constant 
-cause  of  increased  elevation — Delta  extension.  Now  the  in- 
creased momentum  resulting  from  concentrated  flow,  in  dis- 
placing an  increased  amount  of  sea-water,  operates  necessarily 
farther  out  at  sea  ;  and,  in  so  operating,  bears  the  material  of 
river-flow  more  thoroughly  within  the  distributing  influence  of 
the  Ocean-currents.  The  Amazon  with  its  single  outlet  rushes 
into  the  sea  with  a  momentum  that  forces  its  earth-laden  water 
out  into  the  Atlantic  Ocean  for  300  miles.  The  sea  left  thus  to 
dispose  of  the  material  brought  down  by  that  great  river,  the 
Amazon  has,  as  a  consequence,  no  Delta.  Concentration  of  its 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  47 

waters  will  accomplish  like  results  for  the  Mississippi ;  and  in- 
deed the  Mississippi  is  much  more  favorably  circumstanced  for 
the  accomplishment  of  those  results,  in  consideration  of  the 
direction  and  position  of4ts  outflow  in  reference  to  that  great 
distributing  agency — the  Gulf-stream.  The  availability  of  the 
Gulf-stream  as  a  distributor  for  the  Mississippi  may  be  inferred 
from  the  words  of  Sir  Charles  Lyell :  "  that  drift  timber  from 
the  Mississippi  is  carried  to  the  shores  of  Iceland  and  Europe, 
and  that  the  fine  sediment  at  the  velocity  of  the  Gulf-stream 
would  reach  the  point  of  Florida  before  sinking,  and  what  was 
not  deposited  there  would  even  be  carried  much  farther  on." 
Concentration  of  the  water  then  will  not  only  improve  naviga- 
tion by  removing  the  bar  ;  but,  by  increasing  the  momentum, 
will,  in  the  resulting  increase  of  outflow,  lower  the  water-line  : 
and,  in  the  resulting  limitation  of  the  Delta-growth,  will  also 
remove  the  resulting  constant  tendency  to  the  elevation  of 
that  water-line. 

Having  glanced  at  the  special  question  of  the  dredging  of 
the  Mississippi  bar,  it  may  be  excusable  for  glancing  now  at 
another  question  of  the  same  class — Cut-offs.  The  Levee  being 
the  special  object  of  our  consideration  here,  no  other  deviation 
from  it  shall  be  made  than  that  which  it  is  now  purposed  to 
enter  on. 

The  circuitous  character  of  the  Mississippi  and  its  tributa- 
ries is  sometimes  attempted  to  be  remedied  for  the  purposes 
of  drainage,  by  opening  across  the  narrow  part  of  a  bend- 
peninsula  a  direct  channel.  -This  direct  channel  is  known, 
locally,  as  a  "  Cut-off."  Now,  the  current  being  regulated  by 
the  rate  of  fall,  and  the  rate  of  fall  between  any  two  points 
being  regulated  by  the  distance  between  those  points,  the 
shorter  that  distance  the  higher  will  be  the  rate  of  fall,  and  the 
more  rapid  will  be  the  current.  If  the  fall  be  four  feet  from 
the  beginning  to  the  end  of  a  twelve-mile-bend,  then  is  the  rate 
of  fall  in  that  bend  four  inches  in  the  mile  ;  but,  if  that  begin- 


48  PRINCIPLES  AND   PRACTICE   OF 

ning  and  that  end  be  connected  by  a  direct  channel  of  four, 
miles  across  the  bend,  then  is  the  rate  of  fall  increased  to  12 
inches  per  mile.  The  velocity,  all  things  else  being  equal, 
increases  directly  as  the  fall ;  and  hence  does  this  increase  of 
the  rate  of  fall  from  4  to  12  inches  increase  the  velocity,  all 
things  else  being  equal,  three-fold.  But  the -momentum  of  the 
stream,  all  things  else  being  equal,  increases  as  the  square  of 
the  velocity  ;  and  consequently,  when  the  fall  and  velocity  are 
increased  1 J  times,  the  momentum  is  increased  2J  times  ;  when 
it  is  increased  two-fold,  the  momentum  is  increased  four-fold  ; 
and  when,  as  in  the  case  of  the  Cut-off  supposed  above,  the 
fall  and  velocity  are  increased  three-fold,  the  momentum  is 
increased  nine-fold.  Immense  accessions  of  mechanical  effect 
are  thus  seen  to  be  evolved  by  Cut-offs.  Now,  in  ascending 
the  Mississippi,  a  steamboat  encountering  a  current  of  five 
miles  an  hour,  expends  in  the  encounter  a  mechanical  effect  of 
suppose  25  ;  then  will  that  same  steamboat,  in  encountering  a 
current  of  six  miles,  expend  a  mechanical  effect  of  36  ;  in 
encountering  a  current  of  seven  miles,  expend  a  mechanical 
effect  of  49  ;  in  encountering  a  current  of  eight  miles,  a 
mechanical  effect  of  64.  Navigation-resistances  running  up 
thus  rapidly  for  every  increase  of  current — or  shortening  of 
channel — the  point  is  soon  reached  by  such  shortening,  where 
steam-power  becomes  totally  absorbed.  Thus  then,  do  Cut-offs 
endanger  the  continuance  of  navigation.  This  abstract  reason- 
ing, very  true,  is  disturbed  by  the  practical  facts.  If  the  soil 
cut  through  were  indeed  strong  enough  to  withstand  the  accel- 
erated current,  that  acceleration  would  continue  to  act  through 
a  proportionally  contracted  cut ;  but  after  a  while,  the  effect 
of  this  acceleration,  in  the  constant  tendency  of  the  flow  to 
adapt  itself  to  the  material  of  the  banks,  tells  in  the  gradual 
widening  of  the  new  channel  to  something  like  the  general  section 
of  the  river.  With  ordinary  sections  thus  obtained  for  itself, 
the  full  effect  of  shortenings  on  the  increased  rate  of  flow,  con- 


EMBANKING  LANDS  FROM  EIYER-FLOODS.  49 

sequent  on  increased  rate  of  fall,  can  apply  under,  only  the 
supposition  of  free-outflow  at  the  lower  end  of  the  Cut-off,  and 
accelerated  supply  at  the  upper  end.  The  engorgement  of 
the  channel  below  and  the  exhaustion  of  the  channel  above, 
tend,  it  is  true,  to  divide  the  effect  of  the  Cut-off  between  an 
increase  in  the  velocity  within  it,  and  a  lowering  of  the  water- 
line  from  its  lower  end  to  a  point  considerably  up-stream. 
This  modification  of  the  fact  of  increased  velocity,  however, 
must  not  be  held  to  obviate  it  altogether.  Cut-offs,  notwith- 
standing the  corrective  influence  of  channel  widening,  of 
engorgement  below  and  of  exhaustion  above,  tend  by  their 
rapid  rate  of  acceleration  in  river-resistances  to  embarras, 
and  under  circumstances  perfectly  supposable,  even  to  exclude 
navigation.  Every  impediment  to  navigation  involves  an  addi- 
tion to  the  cost  of  shipment ;  and  hence  do  the  planters  who 
seek  relief  from  a  Cut-off,  entail  (until  at  least  the  river  shall 
have  restored  its  disturbed  bank-current  equilibrium)  on  all 
shippers  up-stream  a  greater  or  a  less  increase  of  shipment-tax 
on  their  up-stream  freights.  A  Cut-off,  then,  may  thus  not 
only  put  a  whole  country  under  contribution,  but  may  actually 
deprive  it  altogether  of  the  benefits  of  water-carriage. 

But  navigation  is  not. the  only  interest  involved  in  protesting 
against  Cut-offs.  Increased  velocity  introduced  at  any  part  of 
the  river-channel,  while  the  velocity  below  that  part  remains 
undisturbed  perse,  the  result  will  be  that  the  waters,  deposited 
at  the  termination  of  the  increased  velocity  more  rapidly  than 
they  can  be  passed  off  by  the  receiving  velocity,  will,  as  com- 
pared with  their  reduced  level  within  the  Cut-off,  be  "ponded"  up. 
True,  the  additional  momentum  received  by  the  volume  of  less 
velocity,  will  increase  that  velocity  until  at  some  distance  down 
stream  the  effect  of  that  additional  momentum  shall  have  been 
exhausted.  This  fact  does  not  destroy  the  fact  of  "  ponding" 
up,  but  by  reducing  the  "  ponding"  at  the  point  of  termination 
of  the  specially  accelerated  velocity  pushes  farther  down  stream 


50  PRINCIPLES   AND    PRACTICE   OP 

— to  the  point  of  exhaustion  of  the  additional  momentum  of  the 
special  acceleration — the  point  of  greatest "  ponding."  The  up- 
stream result  may  now  be  glanced  at.  Passing  off  the  water  at  a 
velocity  more  rapid  than  that  at  which  it  is  received,  the  Cut- 
off after  a  while  reduces  the  level  of  the  water  in  the  old-chan- 
nel ;  and  this  reduction  of  level,  accompanied  under  the  "  suc- 
tion" of  the  Cut-off  with  an  accelerated  velocity,  extends  up- 
stream to  a  point  at  which  the  Cut-off  "  suction"  ceases  to  act. 
The  Cut-off  then  alters  the  water-level  to  a  sort  of  concave 
curve,  beginning  up-stream  and  ending  down-stream,  the  deep- 
est depression  being  within  the  Cut-off  itself.  This  curve 
extends  along  the  whole  length  of  increased  velocity  of  the 
flow — that  increase  ending  up-stream  at  the  point  where  the 
"suction"  of  the  depressed-level  of  the  Cut-off  ceases,  and 
ending  down-stream  at  the  point  where  the  accelerated  momen- 
tum of  the  increased  fall  or  velocity  terminates.  The  Cut-off 
then,  is  undoubtedly  servicable  in  lowering  the  water-line 
between  those  extreme  points,  the  lowering  in  the  Cut-off  itself 
being  greatest ;  nor  is  it  open  to  the  drawback  charged  upon 
it  popularly  of  overflowing  the  country  down-stream.  The 
increased  velocity  of  the  Cut-off,  being  accompanied  with  a  re- 
duction of  level,  discharges  no  greater  quantity  of  water  in 
the  same  space  of  time  than  that  discharged  by  the  original 
velocity,  and  original  volume.  How,  indeed,  can  the  Cut-off  be 
supposed  to  discharge  more  water  than  it  receives,  or  to 
discharge  water  more  rapidly  than  that  water  is  received  ?  It 
discharges  only  the  quantity  it  receives  ;  and  receives  only  the 
quantity  that  time  for  time  had  been  received  and  discharged 
by  the  original  volume.  The  popular  objection  to  an  occa- 
sional Cut-off  of  flooding  down-stream  is  seen  thus  to  be 
unfounded.  And  here  it  may  be  observed  that  in  considering 
the  effects  of  Cut-offs  on  navigation  as  well  as  on  discharge,  the 
remarks  made  in  each  case  have  been  confined  to  occasional 
Cut-offs.  A  system  of  Cut-offs  carried  up-stream  to  the  supply 


EMBANKING  LANDS  FROM   RIVER-FLOODS.  51 

points  of  the  rain-basin  would,  however, — until  the  river 
should  have  re-established  its  original  regime,  or  until  the 
surcharged  channel  should  have  worked  out  those  modifica- 
tions of  depth,  by  which  rivers  usually  dispose  of  accumulated 
waters — present  the  question  of  discharge  in  another  light : 
for  the  shortenings  of  150  miles  in  the  lower  reaches  of  Red 
River  point  to  a  continuance  of  those  shortenings  to  an  extent 
that  will  cause  the  delivery  of  the  flood-waters  of  that  River  in 
three  or  four-fold  volume  into  the  Mississippi.  This  occurring 
at  periods  of  like  delivery  in  the  other  tributaries  of  the 
Father  of  Waters — all  discharging  under  the  acceleration  of 
Cut-offs — the  result  would,  until  at  least  the  river  should  have 
adjusted  its  depth  to  its  accumulated  floods,  threaten  along  the 
whole  Delta  of  the  Mississippi  terrible  inundations. 

Grave  objection  rests  also  against  Cut-ofFs  in  the  extent  and 
degree  of  their  increase  in  the  velocity  of  river-flow.  There 
is  as  suggested  already  a  sort  of  balance  between  the  cohesive 
strength  of  a  river  bank  and  the  abrasive  energy  of  a  river- 
current.  When  the  current  exerts  on  the  bank  an  energy 
greater  than  the  cohesive  resistance  of  the  bank,  the  result  is 
expressed  in  caving,  shoals,  bars,  and  alterations  of  channel. 
The  tendency  of  a  river  is  to  go  on  making  changes  in  its 
course  until  the  equilibrium  between  the  strength  of  the  bank 
and  of  the  current  are  fixed  ;  and  this  equilibrium  is  one  of 
the  prime  objects  of  the  river  in  endeavoring  to  establish  its 
regime.  In  rocky  channels,  streams  dash  over  cataracts  ;  in 
beds  of  boulders  and  compact  gravel  they  rush  along  in  almost 
foaming  rapids  ;  whereas  within  alluvial  banks  they  invariably 
sink  down  into  a  gliding  flow.  In  the  latter  case  the  total  fall 
may  show  a  high  rate  of  descent  ;  but  the  result  of  dispropor- 
tionate velocity  over  the  soft  soil  has  settled  down,  after  run- 
ning through  since  the  dawn  of  creation  the  programme  of 
bars,  and  shoals,  and  caves,  and  lakes,  and  new  channels,  and 
old  channels,  into  the  sinuosities  of  to-day.  Nature  in  all  this 


52  PRINCIPLES  AND   PRACTICE   OF 

is  working  by  rule — a  rule  that,  however  it  may  be  modified, 
can  in  no  case  be  safely  broken.  The  Cut-off  then  is  a  direct 
interference  with  the  constantly  operating  law  that  rivers  are 
in  eternal  progress  towards  their  regime.  By  disturbing  the 
balance  of  flow-strength  and  bank-strength,  as  struggled  to  by 
centuries  of  natural  operation,  the  Cut-off  simply  succeeds  in 
throwing  back  the  progress  of  final  result  on  the  part  of  the^ 
river  into  the  early  stages  of  the  world.  Nature  at  once  sets 
about  defining  its  laws  in  such  cases  ;  and  hence  do  Cut-offs, 
in  accelerating  the  energy  of  river-forces,  endanger  from  end 
to  end  of  their  resulting  increase  of  velocity,  violent  changes 
of  bank  and  bed.  No  Cut-off  then  can  for  any  time  continue 
to  be  the  bed  of  the  Mississippi  River  while  the  soil  of 
the  Cut-off  is  mere  soft  alluvium.  Cavings  of  the  most 
formidable  character  must  be  the  consequence  ;  and  extending 
from  end  to  end  of  the  increased  velocity  consequent  on  the 
Cut-off — receiving,  however,  their  greatest  development  in 
the  Cut-off  itself— it  is  quite  impossible  to  tell  where  they 
may  begin  or  in  what  form  of  evil  they  may  terminate. — 
On  Red  River  they  may  result  in  the  restoration  of  its 
ancient  outlet  to  the  Gulf;  and  thus  flooding  the  whole  of 
Western  Louisiana,  turn  with  the  characteristic  suddenness  of 
a  torrent  into  the  Atchafalya.  On  the  Lower  Mississippi  the 
Cut-off  may  reduce  to  a  permanent  swamp,  either  the  valley  of 
the  Yazoo,  of  the  Lower  White  River,  of  the  Lower  Arkansas, 
of  the  Lower  Red,  or  by  causing  the  diversion  of  the 
Channel  into  Manchac,  may,  in  twenty-four  hours  of  its 
flood-season,  reduce  the  whole  of  Eastern  Louisiana  from 
a  teeming  plantation  to  a  miserable  Lagoon.  The  Cut- 
off then,  while  undoubtedly  calculated  to  lower  the  adjoin- 
ing flood-level  for  the  moment,  is  highly  dangerous  to 
navigation,  and  still  more  highly  dangerous,  whether  as  an 
agent  of  accelerated  aggregation  of  water,  or  of  accelerated 
velocity  of  flow — to  all  the  great  interests  of  life  and  property 
on  the  rich  alluvium  of  the  Mississippi  Delta. 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  53 


CHAPTER    III. 

THE     LEVEE. 

WATER  standing  in  a  vessel  or  enclosure  of  any  kind,  presses 
with  equal  force  on  the  bottom  and  the  sides.  At  ten  feet 
deep  the  pressure  of  a  column  of  water  of  a  foot  square  is  the 
weight  of  that  column — 10  cubic  feet  at  62J  Ibs.  per  cubic 
foot — 625  Ibs.  The  bottom  of  the  vessel  containing  this  water 
of  ten  feet  deep,  bears  a  load,  therefore,  of  625  Ibs.  to  the 
square  foot ;  and  the  sides  of  the  vessel  at  the  junction  with 
the  bottom,  bear  the  same  strain.  The  pressure  of  standing 
water,  it  will  be  seen  from  this  explanation,  increases  as  its 
depth  ;  being  for  20  feet  deep,  1250  Ibs.  to  the  square  foot ; 
for  40  feet  deep,  2500  Ibs.  to  the  square  foot  ;  and  this  press- 
ure is  for  the  same  depth,  precisely  the  same,  square  foot  for 
square  foot,  at  the  sides  as  at  the  bottom.  The  width  of  water 
it  will  be  seen  from  this  proposition  has  no  influence  whatever 
on  its  m?e-pressure  j  the  width  of  the  Atlantic  Ocean,  exerting 
only  the  same  hydrostatic  pressure  on  the  shores  as  a  mere 
thread  or  film  of  water  of  the  same  depth.  The  popular  opin- 
ion that  the  width  of  the  Mississippi  affects  a  proportional 
pressure  on  the  Levee,  it  may  be  remarked  here  is  an  error. 
The  side  pressure,  or  in  other  words,  the  weight  of  the  water- 
column  at  the  several  points  of  its  depth,  goes  on  increasing 
from  the  surface,  where  it  is  nothing,  to  the  end  of  the  first 
foot  of  depth,  where  it  is  62J  Ibs.  to  the  square  foot  of  side  ; 
to  the  end  of  the  second  foot,  where  it  is  125  Ibs.  to  the  square 


54  PRINCIPLES   AND   PRACTICE   OF 

foot  of  side  ;  and  so  on,  the  side  pressure  at  any  depth  being 
for  every  square  foot  of  side,  the  product  of  62  J  Ibs.  multiplied 
by  the  number  of  feet  in  depth  of  the  point  at  which  it  is  requir- 
ed to  find  that  side-pressure.  Supposing  them  to  be  exempt 
from  the  blows  of.waves,  and  of  currents,  the  pressure  exerted 
on  Levees  would  then  be  in  the  proportion,  &t  every  foot  from 
its  top,  of  1,  2,  3,  4,  5 — a  regular  arithmetic  progression  from  0 
at  the  top,  to  the  base — the  section  representing  pressure 
being  thus  at  the  base,  the  same  number  of  feet  in  width  as  the 
water  is  in  depth.  This  gradation  of  pressure  in  standing 
water  at  its  several  depths,  presents  the  following  geometri- 
cal form : 


The  pressure  of  the  Mississippi  then,  on  its  banks — rejecting 
that  from  the  blows  of  waves,  or  of  currents — varies  at  the 
several  depths  as  the  widths  vary  in  the  above  figure  ;  and 
hence  will  that  pressure  be  resisted  effectively  by  any  earthy 
matter,  impervious  to  water,  embanked  in  the  above  form. — 
Any  earthy  matter,  provided  it  be  impervious  to  water,  piled 
up  in  the  above  form,  will  discharge  the  quiescent  pressure  01 
the  water,  because  oil  earthy  matter  is  heavier  than  water  j 


EMBANKING  LANDS  FROM  KIVER-FLOODS.  55 

and  consequently  the  above  section  if  made  of  water,  will  not 
exert  a  pressure  able  to  overcome  the  dead  weight  of  the 
above  section,  if  made  of  earth  or  other  material  heavier  than 
water.  But  this  reasoning  rejects  all  other  pressures  of  the 
river  than  its  pressure  as  standing  water.  -Great  forces,  how- 
ever, at,  especially,  the  first  few  feet  in  depth  are  exerted  on 
Levees,  over  and  above  the  standing  pressure,  by  the  incidents 
of  waves  and  currents.  A  direct  cross-wind,  in  a  reach  of  a 
mile  wide,  discharges  the  dead-weight  of  the  water  upon 
the  bank  with  the  velocity  of  a  wave  ;  and,  therefore,  occasions 
a  great  accession  to  the  standing  pressure  of  the  water  for  the 
depth  of  that  wave.  The  steamboat  of  the  Mississippi,  as 
another  producer  of  wave-motion,  is  also  an  agent  converting 
the  standing  pressure  into  a^multiple  of  that  pressure  by  veloc- 
ity |  but  the  steamboat-wave,  acting  on  the  Levee  obliquely, 
produces  an  increase  of  pressure  proportionately  less  than  that 
produced  by  the  wave  striking  it  under  the  impulsion  of  a 
wind  blowing  against  the  Levee  directly.  No  practical  mea- 
sure of  this  particular  cause  of  increased  pressure  on  Levees 
is  obtainable  ;  and,  therefore,  is  this  cause  disposed  of  here 
without  any  attempt  to  estimate  its  measure,  in  the  form  of  a 
specific  quantity.  The  wave-blow,  whether  resulting  from 
wind  or  boat,  is  a  contingency  of  Leveeing  that  must  be  met, 
as  involving  an  unavoidable  necessity  of  increase  on  the  size  of 
Levees,  over  and  above  that  necessary  to  balance  the  pressure 
of  standing  water.  The  other  head  of  increased  pressure,  over 
and  above  the  standing  pressure  on  Levees,  is  that  of  current- 
blows.  Previously  to  this  the  force  of  currents  has  been 
referred  to  in  general  terms  ;  but  in  order  to  express  the 
importance  of  that  force  in  the  present  case  more  fully,  it  may 
be  well  to  present  it  here,  in  the  form  of  a  specific  quantity. 
Mechanical  effect  is  measured  in  the  compound  quantity  of  the 
weight  moved,  and  the  distance  through  which  it  is  moved. 
"  Feet-pounds"  is  the  denominational  term  employed  to  ex- 


56  PRINCIPLES  AND  PRACTICE  OF 

press  this  effect.  100  Feet-pounds  represents  the  mechani- 
cal effect  expended  in  removing  100  Ibs.  one  foot,  or  10  Ibs. 
ten  feet,  or  1  pound,  one  hundred  feet — the  mechanical  effect 
expended  being  in  each  of  these  cases,  the  same  in  quantity. 
A  current  striking  directly  at,  say  6  miles  an  hour,  strikes  with 
a  velocity  of  8J  feet  a  second.  This  8J  feet  multiplied  by 
itself,  (or  squared)  gives  a  product  of  72J,  and  this  72j  divided 
by  the  constant  quantity  64*4,  shows  a  quotient  of  1|.  The 
quotient  so  obtained  is  an  abstract  quantity,  representing  the 
multiple  necessary  to  apply  to  the  dead  weight  of  the  striking 
body  in  Ibs.,  in  order  to  bring  it  for  a  velocity  of  six  miles  an 
hour,  to  its  mechanical  equivalent  in  feet  Ibs.  Suppose,  now, 
that  a  current  acts  at  a  velocity  of  6  miles  an  hour  for  a  section 
of  20  feet  deep,  then  the  gross  average  pressure  of  this  section 
on  the  bank,  as  for  standing  water,  being  625  Ibs.  per  foot,  in 
length,  the  mechanical  effect  expended  against  the  Levee  will 
be,  for  every  foot  in  length,  625  multiplied  by  1|,  or  700  feet 
Ibs.  The  mechanical  effect  that  will  move  700  Ibs.  one  foot, 
will  move  8,400  Ibs.  one  inch-;  and  there  being  little  or  no 
elasticity  in  a  solid  bank  of  earth,  the  current-blow  that  forces 
it  back  a  couple  of  inches — repeated  as  that  current-blow  must 
be  assumed  to  be — may  be  held  sufficient  to  force  it  back 
altogether  ;  and  therefore,  finally,  to  sweep  it  away.  Such  then 
is  the  practical  value  in  Leveeing  of  the  force  of  currents. 
The  wave-blow,  as  has  been  remarked,  is  an  unavoidable  con- 
tingency of  Leveeing,  but  then  it  must  be  recollected  that 
while  some  observers  go  to  the  extent  of  alleging  that  waves 
do  not  involve  any  increase  whatever  of  pressure  latterly,  be 
that  pressure  what  it  may,  it  is  at  all  events  confined  to  the 
height  of  the  wave — a  height  that  in  the  extreme  case  on  the 
Mississippi  does  probably  not  exceed  18  inches.  The  wave-blow, 
then,  involves  no  very  formidable  accession  to  the  strength 
of  the  Levees.  Current-shocks,  however,  are  of  a  very  different 
character  ;  but  on  the  other  hand,  unlike  the  wave-blow,  are 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  57 

altogether,  or  to  a  great  extent,  avoidable.  The  force  of  a 
wave  and  the  shock  of  a  current  represent  the  aggregate 
pressure  that  maybe  brought  to  bear  under  the  most  unfavor- 
able circumstances,  in  Swelling  the  dimensions  of  the  Levee 
beyond  the  form  required  under  the  above  reasoning,  for  the 
pressure  of  quiescent  water. 

The  time  will  come  when  flood-waters  will  be  excluded  from 
the  magnificent  low-lands  of  the  Mississippi,  at  the  cost  of  haul- 
ing, from  wherever  it  can  be  obtained  most  conveniently,  the 
best  material  for  embankments.  The  material  at  hand  will 
continue  to  be  used  for  some  time  ;  and  therefore  does  it 
become  a  matter  of  necessity  to  use  it  with  a  knowledge  of  its 
advantages  and  its  disadvantages.  Sand,  loam,  and  clay  are  the 
materials  at  present  employed  for  the  construction  of  Levees, 
the  loam  and  clay,  unfortunately,  in  small  quantities.  The 
weight  of  water,  it  will  be  recollected,  is  62J  Ibs.  to  the  cubic 
foot ;  whereas  that  of  light  sand  is  95  Ibs.  to  the  cubic  foot ; 
of  loam  124  Ibs.  to  the  cubic  foot  ;  and  of  stiff  clay  135  Ibs. 
With  such  a  difference  as  that  between  95  and  135  in  the  mate- 
rials found  at  different  points,  it  becomes  a  matter  of  importance 
in  designing  the  cross-section  of  large  Levees,  to  consider  the 
specific  gravity  of  the  material  to  be  used.  A  varying  cross- 
section  of  Levee  is  consequently  a  necessity  of  a  varying  soil. 
The  Commissioner,  it  may  be  observed  here,  was  censured  at 
the  time  by  some  parties  for  having  given  the  Levee  across  the 
Yazoo  Pass  and  Levees  of  that  locality,  a  larger  cross*-section 
than  that  previously  adopted  as  a  rule  of  general  application  ; 
but  that  gentleman  would  have  made  a  grave  mistake,  for  which 
his  own  judgment  and  perhaps  the  popular  judgment  would 
have  censured  him  to-day,  if  in  determining  the  dimensions  of 
those  Levees,  he  had  not  gone  to  the  full  extent  demanded  by 
safety  on  the  score  of  weight,  in  exceeding  a  standard  that,  if 
well  adapted  to  the  average  material  of  Levees,  was  certainly 
ill  adapted  to  the  only  material  obtainable  in  the  cases  in  ques- 


58  PRINCIPLES  AND   PRACTICE  OF 

tion — principally  light  sand.  But  besides  objections  based 
on  the  gravity  of  the  materials,  others  also  apply,  classifying 
them  into  different  degrees  of  adaptation  for  Levees.  "Wash  and 
percolation  are  two  most  powerful  agents  of  destruction  in  the 
case  of  river-embankments  ;  and  hence,  does  it  become  of  the 
gravest  importance,  where  the  choice  can  -  be  made,  to  select 
such  materials  as  are  most  cohesive  and  impervious.  The  light- 
ness of  a  sand  bank  is  but  a  small  disqualification  for  Leveeing 
compared  with  its  liability  to  wash  and  leak.  Its  "  wash"  is 
not  even  confined  to  wave,  current  and  rain  j  but  is  carried  on 
actively  also  by  the  wind.  Sand  is  liable  not  only  to  run  and 
blow  away  in  a  dry  state  ;  but  in  also  a  wet  state  is  liable  to 
run,  or  "  melt"  like  so  much  sugar.  But  while  its  lightness 
lays  it  open  as  a  material  for  Levees  to  great  objection  on  the 
ground  of  duration,  the  worst  of  its  properties  in  such  works, 
is  its  liability  to  percolation.  A  bank  of  ample  section  to 
resist  the  total  pressure  brought  to  bear  on  it,  when  that  press- 
ure acts  from  the  outside  slope  against  the  whole  weight  of 
the  bank,  will  yield  when  that  pressure  becomes  transferred 
from  the  outside  of  the  bank  to  some  point  or  plane  within  it. 
In  the  latter  case  a  portion  only  of  the  whole  mass  is  engaged 
in  the  resistance  of  the  whole  pressure.  Now  percolation  of 
the  water  into  the  body  of  the  work,  places  the  Levee  under 
these  very  circumstances.  A  thread  or  plane  of  water,  finding 
its  way  into  the  interior  of  an  embankment,  exerts  just  as 
much  pressure  against  the  earth  on  each  side  of  it  as  if  that 
thread  or  plane  were  an  ocean  of  the  same  depth  as  that  thread 
or  plane.  As  this  thread  separates  the  parts  of  the  Levee, 
the  outside  water  fills  up  the  split  or  open  ;  and  thus  preserv- 
ing the  sand  height  of  water  within  the  split,  as  at  the  begin- 
ning of  rupture,  the  Levee  becomes  completely  rent  asunder  ; 
and  thus  reduced  in  its  aggregate  power  of  resistance,  is  finally 
swept  away.  Porous  materials  then  in  water-banks,  no  matter 
what  be  their  weight  in  the  banks,  tend  by  the  insinuation  of 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  59 

water  threads  between  their  parts,  to  destruction  of  those 
banks — this  tendency,  however,  being  greatest  at  the  time  of 
the  construction  of  the  works,  and  least  at  the  time  when  their 
adhesion  shall  have  been,  perfected  by  the  coating  by  deposit 
over  their  external  faces,  and  the  insinuation  by  filtration  in 
their  internal  pores,  of  earthy  matter.  Loam  is  much  better 
for  water  banks  than  sand.  Thirty  per  cent,  heavier,  it  meets 
all  the  conditions  involved  in  Leveeing  on  the  ground  of 
weight  so  much  better  than  sand.  Much  stauncher  in  its 
parts,  it  is  superior  to  sand  in  all  those  serious  objections 
applying  to  sand  for  the  purposes  of  water-tight  embankments. 
The  very  best  of  those  soils  obtainable  under  the  present  prac- 
tice on  the  Mississippi  for  the  purpose  of  river-banks,  is  blue 
clay.  Several  kinds  of  this  clay  are  found  on  the  lines  of  the 
Levee-works  ;  but  they  are  all  subject  to  the  disadvantage  of 
a  greater  or  a  less  admixture  of  fine  sand.  Perfectly  imper- 
vious to  water  as  they  all  are,  the  presence  of  sand  lowers  their 
usefulness  partly  by  involving  a  lighter  weight,  but  mainly, 
and  sometimes  even  to  a  very  serious  extent,  by  giving  them  a 
tendency,  especially  after  frosts,  to  melt  or  run  like  marl  in 
water.  But  notwithstanding  these  draw  backs,  the  clays  of  the 
Mississippi  bottom  furnish  its  very  best  material  for  Leveeing. 
The  different  bulks  necessary  with  different  soils  for  the 
same  Levee,  has  already  been  pointed  out  as  an  item  of  consid- 
eration in  the  use  of  the  materials  entering  at  present  into  Mis- 
sissippi embankments.  The  remarks  under  this  head  were, 
however,  confined  to  the  influence  on  the  subject  of  the  different 
specific  gravity  of  those  materials.  Another  consideration  in  the 
premises  rests  on  the  fact  of  differences  between  their  "  angles 
of  friction,"  or  in  the  differences  between  their  natural  standing 
angles  or  slopes.  Experiments  recorded  in  Engineering 
authors  of  high  personal  and  professional  standing,  set  the 
angle  of  repose,  or  standing  angle,  of  sand  at  an  angle  of  30 
degrees  with  the  horizon  ;  of  firm  loam  of  from  36  to  45  degrees 


60  PRINCIPLES  AND   PEACTICE   OP 

with  the  horizon  j  of  clays  at  55  degrees  with  the  horizon. 
Using  a  form  more  acceptable  to  the  popular  understanding,  it 
may  be  explained  that  those  experiments  show  the  standing 
slopes  of  those  materials  to  be  as  follows  : 

For  Loam 1  foot  high  to  from  Ij  to  1  base. 

For  Sand        ....  l  foot  high  to  If  foot  base. 

For  Clay 1  foot  to  |  foot  base. 

Experiments  of  this  sort  cannot  be  disregarded  ;  and  therefore, 
though  these  figures  do  seem  to  savor  rather  more  of  the  closet 
than  of  the  field  in  the  rapidity  of  those  angles  of  repose,  they 
are  not  to  be  discarded  in  any  reasonings  to  the  practical  exe- 
cution of  earthworks.  Coupling  then  the  different  specific 
gravities  of  sand,  loam,  and  clay,  with  their  different  angles  of 
repose,  an  assimilation  of  the  merits  of  the  three — waving  the 
question  of  wash  and  percolation — may  be  made  in  terms  of 
the  limits  of  haul,  at  which  it  ceases  to  be  economic  to  reject 
sand  on  the  spot  for  loam  and  clay  in  the  distance.  In  order 
to  reduce  the  loosening  and  lifting  of  the  earths  to  a  common 
standard,  let  it  be  assumed  that  what  might  be  saved  under  that 
head  in  sand  as  compared  with  the  other  two,  and  with  loam  as 
compared  with  clay,  are  balanced  by  the  superiority  of  clay 
over  both  the  others,  and  of  loam  over  sand,  in  weight,  strength, 
and  imperviousness.  In  consideration  of  the  vegetable  matter 
permeating  loam,  the  porosity  permeating  sand,  and  the  light- 
ness and  friableness  of  both,  the  advantage  possessed  in  these 
respects  by  clay  are  hardly  overstrained  by  being  set  down  for 
the  present  purpose,  as  fully  equal  to  the  advantages  possessed  by 
sand  and  loam  over  clay,  as  a  material  for  "  borrowing-pits."  The 
retentive  properties  of  clay,  and  in  a  less  degree  of  loam,  may 
be  said  to  increase  the  difficulty  of  excavations  in  that  material 
in  a  flat  country  ;  but  the  clay  of  the  Mississippi  flats,  resting 
'invariably  in  thin  layers  on  sand,  the  shallow  and  wide-cuts 
necessary  therefore,  for  clay-pits,  may  be  made  perfectly  dry- 
by  running  up  through  them  at  starting,  a  narrow  tap-drain  to 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  61 

the  depth  of  the  sand.  Assuming  then  the  three  materials 
equally  costly  for  loosening  and  lifting,  this  equation  of  theL 
merits  may  be  examined  as  a  question  of  haul.  The  following 
figure  shows  in  the  brokea  line,  a  cross-section  of  Levee  having  a 
crown  of  3  feet  wide  and  a  base  of  21  feet — the  side-slopes  cor- 
responding to  the  angle  of  repose  for  sand,  that  is  to  say,  cor- 
responding to  the  least  angle  at 
which  sand  will  stand.  The  white 
line  in  the  figure  shows  a  Levee  of 
clay,  the  crown  being  2  feet  and 
the  base  15  feet — every  part  of  this 
latter  being  deduced  from  the  form- 
er in  proportion  of  the  weight  of 
sand  to  that  of  clay — 95  to  135 — and 
therefore  presenting,  at  all  points, 
a  resistance  to  the  horizontal  thrust 
of  the  water  equal  to  that  presen- 
ted at  corresponding  points  in  the 
larger  section  (the  broken  line)  of 
the  Levee  of  sand.  Two  feet  wide 
at  crown,  for  example,  presents  as 
great  a  resistance  in  the  case  of 
clay,  as  3  feet  wide  does  in  the  case 
of  sand ;  15  feet  wide  at  base  pre- 
senting as  great  a  resistance  with 
the  use  of  clay,  as  21  feet  wide  at 
base  does  with  the  use  of  sand. 
This  figure,  then,  illustrates  the 
effect  of  difference  in  the  weight 
of  the  two  materials  in  regulating 
the  size  of  Levees.  But  this  differ- 
ence is  still  further  increased  un- 
der considerations  arising  out  of 
their  varying  angles  of  repose. — The  increase  of  pressure  has 


62  PRINCIPLES  AND  PRACTICE   OF 

been  already  shown  to  go  on  from  the  top,  under  extreme  con- 
ditions at  an  arithmetical  progression  ;  and  this  arithmetical 
progression  of  Levee-pressures  or  strengths  has  also  been  shown 
to  express  itself  practically  in  an  aggregate  side-slope  of  45 
degrees — a  total  slope  of  one  foot  base  for  each  foot  in  height. 
The  preservation  of  equal  strength  at  all  parts  of  the  Levee  does 
not  require,  therefore,  a  greater  width  under  even  the  most 
unfavorable  circumstances  than   (whatever   may  be   the   pro- 
per width  of  crown,)  side   slopes   from  each  side  of  crown 
at  a  rate   of  one-half  foot  horizontal   to   one   foot   vertical. 
Such  a  section  may  be  said  to  be,  in  general,  the  section  of 
uniform  strength.    The  strength  of  any  thing  being,  according 
to  the  mechanical  axiom,  the  strength  of  its  weakest  part,  an 
excess  of  strength  at  any  one  part  is,  it  is  almost  needless  to 
observe,  a  waste  of  material  in  Leveeing,  and  consequently  a 
waste  of  money.     In  practice,  however,  it  is  impossible  to  con- 
form to  the  section  of  uniform  strength  in  Levees ;  seeing  that  the 
controlling  consideration  rests  in  the  standing  angle  of  material. 
The  standing  angle  of  clay  has  been  set  down  at  eight  inches 
base,  to   one  foot  in  height ;  and,  therefore,  may  be  held  to 
conform  closely 'to  the  section  of  perfect  economy  of  material — 
the  section  of  uniform  strength.    21  inches  of  base  for  every  12 
inches  of  height,  being  the  standing  slope  of  sand,  that  material 
is  seen  in  the  excess  of  its  natural  section  over  the  section  of 
equality  of  strength,  to  involve  in  Leveeing  a  very  large  waste 
of  material ;  and,  therefore,  of  money.     In  a  Levee  having  a 
3  feet  crown,  a  21  feet  base,  and  a  height  of  5.20,  as  shown  by 
the  broken  line  in  figure  2,  the  area  of  cross-section  is  62.40 
square   feet.      This  Levee,  it  must  be  recollected,  is  one  of 
unequal    strength ;    and,  therefore,    measuring    its    effective 
strength  by  its  weakest  part — its  3  feet  crown — we  find  the  limit 
of  its  actual  resistance  to  be,  when  made  of  sand,  as  (3  feet  x 
95  Ibs.)  285.     A  clay  Levee  of  2.11  feet  crown  sloped  down, 
at  the  standing  angle  of  clay,  to  a  base  of  9  feet  for  5.20  feet 


EMBANKING  LANDS  FEOM   RIVER-FLOODS.  63 

high  contains  within  it  the  slope  of  uniform  strength  ;  and 
consequently,  its  crown  being  its  weakest  part,  the  limit  of  its 
effective  resistance  is  as  (2.11  X  135)  284.9.  This  clay  Levee 
of  2  feet  crown,  and  9  feet  base  presents,  then,  precisely  the 
same  resistance  to  water-pressure  as  does  the  same  Levee  of 
the  game  height,  having  a  crown  of  3  feet,  and  a  base  of  21 
feet.  The  cross-section  of  the  clay-bank  in  this  case,  is  29 
square  feet  ;  while,  as  has  been  said  above,  that  of  the  sand  is 
62  square  feet.  But  practice  goes  still  further  in  increasing 
this  disproportion  between  the  different  quantities  necessary 
in  Levees  of  sand,  and  in  corresponding  Levees  of  clay.  The 
standing  angle  as  presented  in  theory,  must  be  deviated  from 
in  both  sand  and  clay  to  meet,  in  practice,  the  contingencies 
of  floods  and  rains.  Lighter,  looser,  and  less  adhesive  than 
clay,  the  flattening  of  slopes  in  sand  below  that  of  the  angle, 
or  slope  of  repose,  must  be  much  more  considerable  in  practice 
than  that  in  the  heavy  concreted  and  adhesive  bank  of  clay,  to 
resist,  without  endangering  the  effective  strength  or  stability 
of  the  bank,  the  active  washes  of  rains  and  waves.  The  prac- 
tice, however,  in  these  cases  is  so  loose  and  various,  that  it 
cannot  be  expressed  safely  by  a  rule.  Disregarding  it 
altogether,  however,  and  confining  the  equation  of  the  two 
materials  to  the  simple  fact  of  the  difference  between  their 
strict  standing  angles,  26  yards  of  clay  are  seen  to  be  equal  in 
a  Levee  of  5  feet  high,  to  58  yards  of  sand  in  accomplishing 
the  object  of  all  Levees — effective  resistance  to  floods.  In  a 
Levee  of  10  feet  high,  43  yards  of  clay  are  as  effective  as  102 
yards  of  sand  ;  and  in  a  Levee  of  15  feet  high,  60  yards  of  clay 
accomplish  all  the  purposes  of  146  yards  of  sand.  At  15  cents 
per  cubic  yard,  the  difference  in  money  between  the  employ- 
ment in  a  10  feet  Levee  of  43  yards  of  clay,  and  the  corres- 
ponding quantity  of  sand,  is  $8.85  in  favor  of  the  employment 
of  clay.  Supposing,  under  this  view  of  the  case,  the  sand  to 
be  found  on  the  site  of  the  Levee,  while  the  clay  cannot  be 


64  PRINCIPLES   AND   PRACTICE  OP 

obtained  without  haulage  from  some  distance,  the  great  objec- 
tion to  the  employment  of  sand  for  this  purpose,  suggests  the 
enquiry  :  to  what  distance  are  the  parties  interested  bound  by 
the  foregoing  considerations  to  haul  clay  to  their  Levees  ? 
$8.85  are   available,  it  has  been  shown  under  the  foregoing 
comparison,  for  expenditure  in  obtaining  the  clay  as  compared 
with  the  cost  of  the  sand  on  the  spot ;  and  this  $8.85  distribu- 
ted over  43  yards  of  clay,  shows  an  available  amount  for  the 
haulage  of  clay  of  20  cents  per  cubic  yard  of  clay.     In  numer- 
ous instances  this  rate  per  yard  will  cover  all  the  inconvenien- 
ces of  haulage  to  the  Levees,  for  a  distance  of  half  a  mile.     To 
sum  up  these  remarks  :   it  may  be  concluded  that,  supposing 
sand  to  be,  under  any  necessity  whatever,  fit  material  for  the 
construction  of  river  embankments,  taking  the  cross-section  of 
equally  strong  Levees  of  the  two  materials,  comparing  those 
cross-sections  according  to  the  data  furnished  in  the  standing 
angles  of  the  materials,  and  setting  down  for  the  moment,  the 
lightness  and  porosity  of  sand,  as  compared  with  the  heaviness 
and  imperviousness  of  clay  as  material  for  water-banks,  at  the 
mere  difference  in  cost  of  excavating  the  two,  all  the  immense 
advantages  of  clay  over  sand,  not  covered  by  the  assumption 
made  here  in  the  case,  may  be  secured  at  the  same  cost  as 
sand,  by  hauling  clay  to  the  site  of  a  Levee  from  a  distance  of 
half  a  mile.    In  practice,  this  undoubted  fact  and  the  impera- 
tive duty  that  it  points  to,  may  be  found  one  of  very  frequent 
and  profitable  application  ;  for,  in  several  cases,  clay  can  be 
found  in  abundance  in  the  Yazoo  Valley,  within  half  a  mile  of 
existing  Levees  of  almost  unmixed  sand.     In  the  bottoms  and 
banks  of  the  creeks  of  the  out-fall  behind  the  Levees,  in  the 
beds  of  the  old  and  dry  lakes,  so  common  behind  those  Levees, 
in  the  hundreds  of  cypress-swamps  in  the  neighborhood  of  the 
works,  and  on  the  surface  of  the  higher  lands,  the  contractor 
will  find  large  quantities  of  strong,  pure  clay.     The  make-shift 
river-embankments  of  the  State  of  Mississippi,  before  those 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  65 

works  took  the  shape  of  a  system,  under  the  strong  and  able 
mind  of  Col.  Alcorn,  have  already  advanced  to  something  like 
scientific  conditions  in  plan  and  section  ;  but  must  make  still 
further  progress  in  order  to  fulfill  all  the  conditions  of  cheap- 
ness and  efficiency.  Progress  in  those  works  points  to  a 
discrimination  in  the  use  of  the  materials  ;  and,  therefore,  to 
considerations  beyond  those  of  the  mere  accident  of  the  soil 
on  which  they  are  to  be  built.  Sand  is,  in  fact,  utterly  unsafe 
in  a  water-bank,  and,  therefore,  unfit  for  any  works  designed 
for  the  protection  of  property  from  overflow.  Break  after 
break,  in  such  Levees,  is  going  on  with  its  lesson  of  instruction 
to  the  necessity  that  first  felt  obliged  to  employ  sand  ;  and  as 
the  property  suffering  from  such  breaks,  becomes  more  and 
more  valuable,  the  time  is  approaching  when  the  question  of 
material  in  the  Mississippi  Levees  will  be  considered  by  the 
owners  of  property  behind  them,  as  a  question  of  insurance. 
Sand  will,  by  and  bye,  be  either  altogether  rejected  in  Levee 
making,  or  used  only  in  positions  where  its  properties  can  be 
turned  to  usefulness  j*  and  in  order  to  open  the  way  for  this 
purpose  in  the  right  direction,  the  general  question  of  its 
merits  as  compared  with  clay  is  here  considered  for  the  infor- 
mation of  the  planter.  The  unthinking  will,  probably,  under- 
value the  reasonings  employed  in  the  case,  as  what  a  certain 
gentleman  in  Mississippi  would  call  "  College"  nonsense  ;  but 
men  of  reflection  will  recollect  that  progress  knows  no  road 
but  that  pointed  out  by  observation,  reflection,  and  calculation. 
Discrimination  between  the  materials  at  hand  is  the  first  object 
aimed  at  in  the  foregoing  remarks  on  those  materials;  the 
haulage  of  the  best  material  for  a  short  distance  is  the  next  object : 
and,  following  that,  the  haulage  of  the  material  to  the  full  extent 
— as  between  sand  and  clay — of  half  a  mile  ;  the  next  step  in 
advance  being  one  that  is  also  yet  to  come — the  total  rejection  of 
sand,  as  a  building  material,  from  the  Levees  of  the  Mississippi. 

*  See  note,  page  80. 

5 


66  PRINCIPLES   AND    PRACTICE   OF 

The  materials  at  hand  will,  however,  continue  to  be  used  for 
some  time  in  the  Mississippi  embankments.  It  becomes,  there- 
fore, important  to  consider  the  best  means  for  reducing  the 
disadvantages  of  their  use  to  the  smallest  possible  amount. 
The  leaky  property  of  sand  is  its  greatest  objection  ;  but  this 
may  be  overcome  to  a  large  extent  by  constructing  within  the 
bank  a  vertical  wall  from  crown  to  base,  of  clay,  thoroughly 
tramped  and  puddled.  This  "  puddle  wall*'  ought  to  contain 
no  vegetable  matter,  such  as  grass  or  roots  of  any  kind  ;  and 
when  wet  to  a  proper  consistency  ought  to  be  shoveled  into 
the  place  left  for  it  in  the  sand-bank  as  the  bank  goes  up, 
layer  after  layer.  When  the  puddle  is  in  its  place  it  ought  to 
be  tramped  down  well ;  it  is  indeed  beaten  down  in  water- 
banks  in  England  and  Ireland  with  a  heavy  maul  or  rammer. 

The  practice  of  cutting  out  a  trench  for  the  puddle,  or 
"  muck  ditch"  as  it  is  called  on  the  Mississippi,  in  the  natural 
surface  of  the  ground,  is  generally  useless,  and  some  times  posi- 
tively mischievous.  Where  retentive  subsoils  exist  under  the 
base  of  the  proposed  bank,  then  it  is  certainly  a  clear  gain  in 
staunchness  to  run  down  the  puddle-wall  of  the  Levee  to  a 
bond  with  the  underlying  impervious  earth.  But  the  experi- 
ence along  the  shores  of  the  Mississippi  leads  to  the  presump- 
tion that,  in  those  cases  where  the  sand  does  not  commence  on 
the  surface,  a  ditch  of  three  feet  deep  is  more  likely  to  present 
a  bottom  of  sand  than  of  loam,  or  clay.  The  rationale  of  those 
"  muck  ditches,"  as  they  are  called  locally,  rests  on  their  use- 
fulness in  preventing  leakage  ;  and,  therefore,  supposing  the 
ditch  and  wall  carried  up  regularly  with  a  puddle,  those 
ditches  in  a  great  majority  of  cases  failing  to  reach  a  more  re- 
tentive soil  than  that  at  the  surface  of  the  ground,  involve  in 
all  those  cases  an  utterly  resultless  waste  of  money.  Besides, 
to  undertake  to  prevent  leakage  through  the  porous  earths  of 
the  natural  shores  of  the  river,  is  a  hopeless  labor  ;  and  so 
far  as  the  strength  and  durability  of  the  Levees  are  concerned 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  67 

is  a  labor,  also,  perfectly  useless.  It  accomplishes  nothing 
whatever,  for  the  artificial  embankment.  But  in  some  cases 
these  "  muck  ditches"  are,  as  already  stated,  mischievous. 
Across  those  lagoons  or  -creeks  which  are  dry  during  periods  of 
low-water,  the  foundation  for  banks  consists  generally  of  a  hard 
crust  of  clay  for  a  few  feet  thick,  overlying  quicksands  or  thin 
puddles.  These  crusts,  like  the  grillage  of  timbers  used  for 
the  foundations  of  some  Engineering  works,  are  highly  valuable 
in  those  situations,  by  diffusing  the  weight  of  the  superincum- 
bent Levee  over  a  wide  bearing  ;  and  thus,  though  unequally 
loaded  by  the  necessary  cross-section  of  the  Levee,  assist,  in 
proportion  to  their  strength,  to  distribute  that  bearing  equally. 
This,  where  not  sufficient  to  obviate  the  sinkage  altogether, 
reduces  it  considerably  ;  and  in  bringing  a  large  area  to  act  in 
the  resistance,  assists  to  guarantee  with  the  least  possible 
"sinkage,"  and,  therefore,  least  possible  loss  of  work — of  money 
— a  finally  well-sustained  foundation.  The  "  muck  ditch,"  how- 
ever, cuts  this  natural  platform  for  the  Levee  in  two  parts  ; 
and  over  this  cut,  the  greatest  weight — that  at  the  crown — 
pressing  vertically,  acts  as  with  a  leverage  in  bending  down, 
and  finally  breaking  off  the  natural  crust  of  the  surface.  The 
necessity  therefore  follows,  under  those  circumstances,  of  em- 
ploying an  excess  of  earth  in  forcing  out  laterally,  and  forcing 
down  vertically,  the  running  sand  or  soft  puddle  of  the  underly- 
ing foundation  in  order  to  compress  those  soft  materials  into  a 
compactness  sufficient  to  present  an  effective  resistance  to  the 
weight  of  the  superincumbent  embankment. 

Rejecting  then  the  practice  of  cutting  a  muck  ditch  along  the 
base  of  the  Levee,  it  is  recommended  here  that  the  earth  of 
the  base  be  loosened  for  six  or  twelve  inches  in  order  to  secure, 
between  the  artificial  and  the  natural  bank,  a  proper  bond. 
Indeed  where  the  natural  surface  is  loam  or  clay  for  any  con- 
siderable depth,  it  would  be  highly  judicious  in  order  to  prevent 
grasses  or  other  vegetable  matter  of  retarding  the  bond  between 


68  PRINCIPLES  AXD   PRACTICE   OF 

the  Levee  and  the  ground,  to  skim  the  surface  ;  and  one  good 
purpose  thus  served,  the  sod  so  skimmed  off  the  base  may,  on 
the  completion  of  the  Levee,  realize  the  further  good  purpose 
of  staunching  it  by  laying  them  in  a  close  coating  on  its  water- 
slope.  Be  the  substitute,  however,  for  the  muck  ditch  what  it 
may,  the  present  practice  in  the  case,  if  even  not  useless  and 
unsafe,  is  certainly  absurd  when  it  is  recollected  that  it  is  in 
fact  a  "  muck  ditch  "  with  the  important  exception  of  the  "  muck." 
The  lightness  of  sand  is  a  great  objection  against  the  use  of 
that  material  in  water-embankments.  Sand  is  constantly  carried 
away  in  immense  quantities  by  the  current  of  the  Mississippi ; 
and  therefore,  to  invest  money  in  banks  of  sand  for  the  exclu- 
sion of  the  Mississippi  floods,  does  not  seem  to  be  a  policy  very 
remarkable  for  its  astuteness.  As  its  porosity  presents  the 
use  of  sand  in  Levees  in  the  shape  of  a  question  of  safety,  its 
lightness  presents  its  employment  in  those  works  in  the  shape 
of  a  question  of  maintenance.  Rains  constantly  washing  the 
particles  in  its  crown  down  to  its  sides  ;  and  washing  those  in 
its  sides  out  upon  its  base,  the  weakest  part  of  a  Levee — the 
crown — is  undergoing  constant  reduction  in  its  dimensions, 
and  consequently  in  its  strength.  Current-washes  and  wave- 
washes  on  the  water-side  co-operate  in  times  of  high-water  with 
the  rain-wash  at  other  times,  in  reducing  the  strength  of  Levees 
thrown  up  in  sand.  Maintenance  becomes  thus  in  the  case  of 
sand  Levees,  a  serious  outlay.  To  remedy  this — and  indeed  at, 
the  same  time  assist  its  want  of  imperviousness — the  most  con- 
venient course  is,  to  cover  the  water-slope  of  such  banks  with 
as  thick  a  layer  as  may  be  obtained  of  clay,  if  obtainable,  -or  if 
not  with  as  thick  a  layer  as  may  be  laid  on  according  to  the  above 
suggestion,  from  the  quantity  of  earth  obtainable  by  collecting 
the  loam  of  the  adjoining  surface.  In  Ireland  it  is  very  common 
to  face  water-slopes  with  grass-sods  laid  on  their  flat  beds 
with  regular  headers  and  stretchers,  as  in  Ashlar  work,  the 
whole  being  cut  down  to  the  plane  of  the  slopes.  Under 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  69 

the  direction  of  Mr.  M.  B.  Hewson,  I  have  myselt  conducted 
large  quantities  of  this  work  for  the  Board  of  Public  Works, 
under  the  measures  for  the  drainage  and  navigation  of  Irish 
Rivers.  In  the  South  ""sods  "  are  not  generally  obtainable  ; 
but  all  the  advantages  resulting  from  their  use  in  water-banks, 
may  be  obtained  there  by  sowing  the  seeds  of  some  southern 
grasses  in  a  coat  of  loam-dressing  on  the  slopes  of  those  banks. 
Bermuda  grass  is  well  adapted  for  the  preservation  of  artificial 
banks  ;  but  though  often  employed  for  that  purpose  on  Rail- 
roads in  the  Northern  States,  is  excluded  from  use  on  banks  in 
the  South-west  by  what  would  seem  to  be  no  better  than  a  mere 
prejudice.  The  rapidity  of  its  growth  is  not  the  only  recom- 
mendation for  the  employment  of  Bermuda  grass  on  Levees  ; 
for  it  possesses  the  further  recommendation  of  growing  in  both 
shade  and  sun.  During  high-water  it  will  catch  a  great  quan- 
tity of  sediment ;  and  by  the  consequent  annual  coating  of 
impervious  earth,  will  add  to  the  strength  and  durability  of 
the  Levee.  The  decay  of  the  tops  and  blades  of  this  grass  will 
also  assist  in  covering  the  wrater-slope  of  the  Levee  with  an 
annual  coating  of  impervious  matter,  and  in  the  case  of  Levees 
built  of  sand,  will  thus  tend  greatly  to  the  correction  of  their 
two  great  shortcomings — washing  and  leakage.  A  hedge  ol 
Osage  Orange,  set  closely  along  the  inside  slope,  by  excluding 
both  travelers  and  cattle,  and  a  coat  of  Bermuda  grass  set  on 
both  sides,  by  obviating  wash  whether  of  rain  or  current,  will 
save  the  parties  interested  in  Levees,  a  large  annual  sum  for 
their  maintenance. 

In  Europe,  generally,  it  is  usual  to  protect  embankments  by 
growing  on  their  top  and  sides  thickly  growing  grasses.  In 
parts  of  Holland  straw  is  used  for  the  same  purpose.  Twisted 
into  ropes  about  2  inches  in  diameter,  it  is  laid  on  the  face  of 
the  bank,  and  pinned  down  with  hooked  or  forked  sticks  ;  rope 
after  rope  being  added  each  in  close  contact  to  the  previous 
one  is  so  laid  down  until  the  whole  slope  is  covered  with  a  com- 


70  PRINCIPALS   AND    PRACTICE   OF 

plete  mat  of  straw.  Vegetation  in  course  of  time^commences 
underneath  the  straw,  and  blades  of  grass  making  their  way 
between  the  ropes,  the  whole  becomes  a  compact  sheeting. 
Fascines,  hurdles,  and  brush-wood,  are  sometimes  employed  for 
the  same  purpose.  Large  stone  slabs  are  often  used  by  En- 
gineers in  Bombay  for  the  protection  of  the  slopes  of  heavy 
embankments  from  the  weather.  So  important  is  it  found  in 
experience  all  over  the  world,  when  it  is  worth  while  to  go  to 
expense  in  the  construction  of  embankments,  to  go  to  further 
expense  for  their  efficiency  and  preservation.  Any  thing  that 
is  worth  being  done  in  waiter-works  is  worth  being  done  pro- 
perly and  well. 

The  standing  slopes  that  have  been  given  above  for  sand 
loam  and  clay  are  the  standing  slopes  of  those  materials  when 
dry.  The  dry  slope  and  the  wet  slope  of  all  earths  are,  how- 
ever, more  or  less  different.  The  same  earth  that  stands  in 
practice  at  an  angle  of  2  to  1  in  a  dry  position,  will  require  in 
a  wet  situation  a  slope  of  3  to  1.  Some  earths  have  been 
found  to  require  in  a  wet  situation  slopes  so  low  as  4  to  1.  A 
river  embankment  involves  both  the  two  distinct  conditions  of 
dry  and  wet  slopes — the  inside  being  necessarily  regulated  by 
the  conditions  of  dry  slopes,  the  outside  being  subject  to  the 
tests  applicable  to  icet  slopes.  Wetness  and  dryness,  however, 
do  not  cover  the  whole  difference  between  the  circumstances 
of  the  dry  and  the  wet  slopes  of  the  Levee  ;  for  the  outside 
slope,  in  addition  to  the  disadvantage  of  wetness,  is  also  sub- 
ject to  the  further  disadvantage  of  waves  and  currents.  The 
practical  facts  of  the  case  establish,  therefore,  the  general 
proposition  that  the  external  or  wet  slope  of  the  Levee  ought 
to  be  less  in  rate  than  that  on  the  inside,  or  dry  slope.  If  the 
wet  slope  be  sufficient  for  the  necessities  of  its  position  ;  then, 
to  carry  out  the  dry  slope  at  the  same  rate  is  a  simple  waste 
of  material,  and  consequently,  a  waste  of  money.  In  six  cases 
of  well  known  water-banks  in  England,  the  inside  or  dry  slopes 


EMBANKIXG   LANDS   FROM   RIVER-FLOODS.  71 

vary  according  to  the  material,  from  an  incline  of  1  to  1  to  an 
incline  of  3  to  1,  averaging  an  incline  of  1 J  to  1,  or  about  30 
degrees  with  the  horizon  •  the  outside  or  water-slopes,  in  those 
six  cases,  varying  from  an  incline  of  2|  to  1,  to  an  incline  of  5 
to  1 — the  six  showing  for  the  water-slopes  an  average  incline 
of  about  3|  to  1.  or  about  16  degrees  with  the  horizon.  Natu- 
ral water-slopes,  formed  under  water,  such  as  those  of  bars  in 
the  Mississippi,  or  other  rivers,  vary  from  an  incline  with  the 
horizon  of  from  5  to  30  degrees — the  average  of  these  two 
extremes  being  17J  degrees,  or  nearly  3  feet  of  base  for  every 
foot  in  height. 

The  height  of  a  Levee  above  high- water  mark  has  been  set 
down,  by  practice  along  the  Mississippi,  at  1\  feet,  and  at  3 
feet.     A  Levee  system,  as  has  been  shown  in  another  chapter, 
does  not  occasion  an  immediate   elevation  of  the  previously 
established   flood-level.      General   considerations,   then,   have 
nothing  to  do  with  this  head  of  the  subject,  seeing  that  it  is  a 
head  proper  to  local  specialities.     The  width  of  a  river  and 
the  force  of  the  winds  regulate  the  height  of  its  wind-waves  ; 
while  the  width  and  current  of  the  river,  coupled  with  the 
speed,  load-line,  and  midship  section  of  its  steamboats,  regulate 
the  height  of  its  steamboat-waves.     Two  feet  would,  probably, 
plumb  the  highest  wave  resulting  from  the  accidental  combi- 
nation of  the  greatest  wind-wave  with  the  greatest  steamboat- 
wave  rising  on  the  Levees  of  the  Mississippi.     The  looseness 
of  the  observations  made  as  to  high-water  in  that  river,  coupled 
with  the  further  consideration  that  those  observations  may  not 
go  sufficiently  far   back,  in  time,  to  embrace  that  particular 
combination  of  circumstances  which  produce  the  highest  pos- 
sible flood,  suggest  the  propriety  of  basing  the  height  of  the 
Levees  on  a  margin  over  and  above  the  strict  inch  of  the 
recorded  high-water  mark.     Allowing  24  inches  for  the  height 
of  the  maximum  wave  striking  the  Levee,  12  inches  additional 
is  certainly  not  too  large  an  allowance  for  the  contingencies  of 


72  PRINCIPLES   AND    PRACTICE   OF 

the  case,  in  determining  the  height  above  high-water  of  the 
Mississippi  Levees.  Close  enough,  already,  no  reason  certainly 
appears  to  show  why,  the  standard  of  an  excess  of  3  feet  above 
the  highest  known  flood  should  be  lowered  ;  and  it  is,  there- 
fore, safer  to  conclude  that  experience,  as  in  the  case  of  the 
State  of  Mississippi,  has  settled  the  question  between  economy 
and  safety  in  the  matter,  by  fixing  the  height  of  Levees  at 
three  feet  above  -the  highest  level  of  quiescent  flood  water  in 
the  river.  Four  feet  of  an  excess  would,  of  course,  be  still 
safer. 

The  crown-width  of  Levees  is  a  question  less  of  rule  than 
expediency.  In  England,  water-banks  have  an  average  width 
at  top  of  3  feet.  In  Ireland,  the  top-widths  of  embankments 
for  drainage,  are  about  the  same.  In  Holland,  however,  the 
Dikes,  when  employed  for  road-ways,  are  exceptionally  wide 
across  the  crown.  The  Sea-banks  of  Holland  are,  in  any  event, 
no  guide  in  fixing  on  the  dimensions  of  river-embankments  ; 
nor,  indeed,  are  the  size  of  water-banks  in  England,  or  Ireland, 
quite  a  safe  guide  for  such  banks  when  subject  to  the  wash  of 
the  immensely  heavier  rain-fall  of  the  Lower  Mississippi. — 
Local  experience,  then,  is  the  best,  and  indeed,  the  only  guide 
in  this  matter.  In  Arkansas,  it  is  true  the  local  experience 
has  been  had  under  circumstances  which  make  it  start  from 
too  high  a  point ;  with  the  view  of  a  necessity  for  adapting  the 
section  of  the  Levee  to  the  width  of  the  river,  some  absurd 
and  ignorant  theory  has  led  to  the  rule,  that  all  Levees  in  that 
State  be  as  many  feet  in  width  at  crown  as  they  are  in  height. 
These  works,  however,  have  been  carried  out,  chiefly,  without 
the  guidance  of  professional  skill.  In  the  State  of  Mississippi, 
the  practice  has  settled  down  into  a  width  of  5  feet  for  the 
crown  of  Levees  generally.  My  own  practice  and  experience 
lead  me,  however,  to  the  conclusion  that  3  feet  is  sufficient  to 
cover  all  the  coritingencies  of  rain-washings,  cattle-tramping, 
&c.,  during,  and  for  a  sufficient  time  subsequent  to,  the  harden- 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  73 

ing  and  cementing  of  the  works.  Economy,  however,  in  this 
case,  as  in  that  of  height  and  all  other  dimensions,  is  the  only 
limit ;  for  safety  is  always  the  gainer  by  an  excess  of  section. 

Shrinkage  had  been  included  in  the  considerations  regulating 
cross-sections  in  the  Mississippi  practice.  The  generalizing 
pursued  in  this  case  was  as  erroneous  in  execution  as  in 
that  of  the  "  muck  ditch. "  Different  materials  shrink  in  banks 
differently.  Its  particles — fine  and  loose — sand,  however 
loosely  it  may  be  shovelled  together,  fills  its  space  closely  ; 
and,  therefore,  whether  wet  or  dry,  settles  at  a  very  small  dimi- 
nution of  its  original  bulk.  In  time,  too,  the  process  of  this 
settlement  is  short.  One-tenth  of  its  original  content  is 
a  liberal  allowance  for  shrinkage  in  sand.  Tough  clay,  however, 
is  banked  up  under  different  conditions.  Adhesive  in  its  char- 
acter, it  is  loosened  and  lifted  in  lumps  ;  and  from  the  size  of 
those  lumps,  their  shape,  and  their  resistance  to  a  change  of 
form,  they  fall  together  in  an  embankment  without  compactness. 
Settling  of  such  a  bank  is  the  process  of  filling  up  all  the  cavities 
and  spaces  existing  thus  between  its  parts  ;  and  hence  in  the 
case  of  lumps  so  large  and  stiff  as  those  of  clay  excavations,  is 
the  amount  of  this  settling  quite  considerable — generally  about 
one-fifth  of  its  original  bulk.  The  time  expended  in  the  settle- 
ment of  clay  is  longer  than  that  in  the  settlement  of  sand. 
The  different  modifications  of  material  between  sand  and  cky 
settle  as  to  time  and  quantity,  in  proportion  to  the  respective 
amounts  in  their  constituent  parts  of  sand  and  of  clay.  An 
average  of  16|  per  cent,  then,  the  allowance  generally  made  in 
Mississippi,  waving  the  objection  to  the  principle  in  the  case, 
is  not,  in  all  probability,  a  great  error  on  either  side  from  the 
strict  justice  as  to  the  quantity.  Two  inches  to  the  foot  for  the 
height,  with  proportional  increase  to  the  side  slopes  without 
any  addition  to  the  width  at  base,  is  added  in  practice  to  the 
intended  settlement  section  of  the  Levee,  in  order  to  cover  the 
loss  of  form  and  size  by  "  shrinkage"  or  settlement.  Accord- 


74  PRINCIPLES  AND   PRACTICE   OF 

ing  to  the  variations  in  the  height  of  the  bank  from  the  surface 
of  the  ground  an  addition  of  one-sixth  was  thus  added  on  to 
it,  over  and  above  the  gradient  line  of  3  feet  above  flood. 

The  section  of  a  water-bank  is  a  mixed  question  of  theory 
and  practice.  In  examining  its  several  parts  here,  it  has  con- 
sequently been  found  unavoidable  to  mix  up  the  abstractions 
of  the  subject  with  its  working  facts.  Having,  however,  made 
those  examinations  under  the  several  heads  of  slope,  height, 
and  crown,  the  next  point  to  be  made  is  the  combination  of  the 
results  in  the  elimination  of  the  practical  cross-section.  And 
first  for  sand.  The  .width  of  crown  being  taken  uniformly  at  3 
feet,  the  slopes  of  a  Levee,  showing  the  strict  angles  of  its  stand- 
ing slope,  on  the  inside  for  dry  sand  and  on  the  outside  for  wet 
sand,  is  represented  by  the  light  line  in  fig.  3.  The  broken 
line  represents  the  section  adopted  in  the  present  Levee 
practice  of  the  State  of  Mississippi ;  the  heavy  line  in  that 
figure  representing  the  section  resulting  from  the  employment 
of  the  surplus  material  used  under  that  practice,  in  increasing 
the  resistance  of  the  material  when  distributed  at  the  strict 
standing  slopes  of  the  wet  and  dry  sides  of  the  section,  in  a 
manner  to  produce  an  equal  increase  of  the  resistance  of  the 
material  of  those  slopes  to  motion  from  wind  or  wash.  The 
section,  figure  3,  applies  to  sand.  It  adopts  the  quantities  of 
the  practice  at  present  pursued  in  Mississippi  ;  and  redistri- 
butes those  quantities  on  the  basis  of  the  respective  angles  of 
repose  of  the  material  in  dry  and  in  wet  slopes.  Fig.  4  repre- 
sents a  cross-section  of  equal  strength  with  that  of  fig.  3,  the 
one  being  assumed  to  be  carried  out  in  sand,  the  other  in  clay. 
The  strength  of  the  sand-section  being  assumed  for  its  basis, 
this  clay-section  is  simply  an  addition  to  the  wet  and  the  dry 
slopes  of  repose  of  material  equal  in  quantity  to  the  additions 
made  in  fig.  3,  to  those  slopes  for  sand. 

The  sections  in  the  two  figures  given  here  show  again  the 
relative  proportions  necessary  for  equal  strength  in  clay  and  in 


EMBANKING  LANDS  FROM  RIVER-FLOODS. 


75 


76  PRINCIPLES   AND   PRACTICE   OF 

sand.  The  reduction,  however,  of  the  width  of  crown  from  3 
to  2  feet  in  the  case  of  the  clay  is  objectionable  in  practice. 
The  considerations  presented  when  reviewing  the  practice  pur- 
sued in  this  particular  in  Mississippi  suggest  the  expediency 
of  adopting  the  width  of  crown  in  all  cases,  of  3  feet ;  and  there- 
fore, is  the  section  above  given  on  the  supposition  on  either  the 
inside  or  the  outside  slope  of  a  Levee,  of  an  addition  of  clay 
having  a  uniform  thickness  of  12  inches  as  represented  by  the 
second  heavy  line.  This,  then,  shows  a  Levee  as  compared 
with  that  of  the  section  in  sand,  of  considerably  increased 
strength — the  excess  at  the  point  of  least  resistance — the 
crown — being  over  and  above  the  sand-bank  nearly  50  per  cent. 
The  standing  angle  of  each  material  being  taken  as  the  basis  of 
the  respective  sections,  the  additions  made  to  those  standing 
angles  for  the  purpose  of  increased  stability — the  addition  made 
in  the  case  of  clay  giving  the  same  additional  width  of  base  as 
in  the  case  of  sand— constitute  in  consideration  of  the  superior 
weight  and  adhesiveness  of  the  material,  a  greater  additional 
stability  over  and  above  that  of  the  section  of  the  strict  slopes 
of  repose.  The  resistance  to  weather  and  current  are  greater, 
therefore,  in  the  case  of  a  clay  Levee  of  the  section  shown  in 
fig.  3^  than  of  the  section  shown  in  fig.  4,  thrown  up  in  sand. 
The  rule  adopted  in  Mississippi  for  the  proportioning  of  Levees 
is  seen  to  be  wrong  in  its  recognition  of  equality  of  their  dry 
and  their  wet  slopes.  But  this  rule  is  exceedingly  inconvenient. 
Six  to  one  being  the  proportion  regulating  the  width  of  base 
in  terms  of  the  height  in  the  State  of  Mississippi,  the  base  for 
a  Levee  of  3  feet  is  18  feet,  of  6  feet  is  36  feet,  and  of  12 
feet  is  72  feet.  The  crown  in  each  of  these  three  Levees  being 
5  feet  wide,  the  base  of  the  slopes  themselves  (deducting  the 
width  of  crown)  is  for  the  3  feet  Levee  13  feet ;  for  the  6  feet 
Levee  31  feet ;  for  the  12  feet  Levee  67  feet — the  rate  of  slope 
on  each  side  being  thus  :  for  the  3  feet  Levee  2244  to  1  ;  for  the  6 
feet  Levee  2S  to  1  ;  for  the  12  feet  Levee  2£  to  1.  Every 


EMBANKING   LANDS   FROM  RIVER-FLOODS.  77 

height  of  Levee  is  thus  seen,  under  the  application  of  the  Mis- 
sissippi practice  in  this  particular,  to  present  its  own  peculiar 
slope  ;  and  consequently  does  the  whole  line  of  Levee  in  that 
state  present  a  constant  succession  of  varying  slopes — a  different 
slope  for  every  different  height.     The  inequality  of  the  stability 
resulting  from  these  circumstances  is  a  mere  theoretical  con- 
sideration too  trifling  to  be  regarded  seriously  in  practice.    The 
objectionable  feature  of  the  case,  however,  applies  to  its  practi- 
cal inconvenience  to  the  Engineer  in  estimating  the  quantities 
of  the  work.     At  this  moment  it  does  not  appear  that  calcula- 
tions can  be  made  with  mathematical  exactness  in  such  a  case 
by  any  established  formula  ;  but  be  that  as  it  may,  it  is  very 
clear  that  such  calculations  must  of  necessity  be  tedious  and 
complicated.     The  subject  of  calculation  is,  however,  treated 
more  fully  in  its  proper  place.     The  slopes  ought  to  be  laid 
down  in  terms  of  the  height  exclusive  of  the  width  of  crown — a 
quantity  that  is  a  constant  for  all  widths  of  base.     To  apply  the 
inferences  from  the  sections  given  in  figures  3  and  4  to  meet 
this  expediency  of  equality  of  rate  of  slope  for  all  heights,  it 
may  be  observed  that  those  sections  are  given  for  a  height  of 
seven  feet.     They  show  for  that  height  a  wet  slope,  for  sand  of 
3|  to  1,  for  clay  of  1§  to  1  ;  and  a  dry  slope  for  sand  of  2J  to  1, 
for  clay  of  1}  to  1.     For  a  height  of  10  feet  these  slopes  would 
for  sand  under  the  Mississippi  practice  be  still  flatter.     As  a 
rule  then  of  constant  application  for  all  heights,  these  sections 
may  be  generalized  into  the  following  :  in  clay  the  inside  slope 
to  be  1J  to  1,  the  outside  to  be  1|  to  1  ;  while  in  sand,  the 
inside  slope  is  2J  to  1,  the  inside  3J  to  1.     In  consideration, 
however,  of  the  fineness  of  the  sand  available  along  the  Mis- 
sissippi, and  of  the  greater  or  less  mixture  of  that  sand  in  all 
its  clays,  and  also  in  consideration  of  the  necessity  of  simpli- 
fying calculations  to  the  level  of  the  expertness  superintending 
the  works,  it  is  recommended  here  that  the  rule  for  constructing 
Levees  on  the  Mississippi  be  (as  the  conclusion  of  the  foregoing 
remarks  on  base,  crown  and  material)  as  follows : 


78  PRINCIPLES   AND   PRACTICE   OP 

In  Sand. 

Inside  or  dry  slope  2i  1o  1.  >  oft. 

Outside  or  wet  slope  84  to  1.  \   crown  3  fect 

In  Clay. 

Inside  or  drv  slope  l£  to  1. )  0  f    . 

Outside  or  vet  slope  2  to  1.     }   crown  3  lect 

The  clay-section  supposes  the  rejection  from  the  bank  of  all 
sand.  For  any  admixtures  of  the  two,  no  matter  how  small  the 
proportion  of  that  material  in  the  admixture,  it  would  not  be 
safe  to  deviate  from  the  proportions  recommended  above  for 
sand.  In  order  to  show  the  ease  with  which  this  new  practice 
may  be  substituted  for  the  present  faulty  one,  the  following 
form  of  calculation  is  presented  here  : 

Station.    Height  of  Leveo.    Inside  slope.    Outside  slope.     Crown  width.     Total  width  of  base. 

41.40 
46.20 
43.80 
58.80 
73.20 
81.00 
67.80 
45.60 

To  guard  against  mistakes  in  making  this  calculation,  it  is 
recommended  that  after  copying  from  the  field  notes  the  heights 
corresponding  to  each  station,  each  of  the  other  columns  be 
carried  out  separately.  Otherwise  the  multiple  of  2J  in  the  one 
case  will  be  often  used  by  mistake  for  the  other  multiple  and 
vice  versa. 


2J  to  1. 

3J  to  1. 

I 

6.40 

16.00 

22.40 

3.00 

2 

7.20 

18.00 

25.20 

3.00 

3 

6.80. 

17.00 

23.80 

3.00 

4 

9.30 

23.25 

32.55 

3.00 

5 

11.70 

29.25 

40.95 

3.00 

6 

13.00 

32.50 

45.50 

3.00 

7 

10.80 

27.00 

37.80 

3.00 

8 

7.10 

17.75 

24.85 

3.00 

EMBANKING  LANDS   FROM  RIVER-FLOODS.  79 


CHAPTER    IY. 

DETAILS     OF     LEVEE-WORKS. 

EXPERIENCE  is  made  up  in  Leveeing,  as  in  all  other  works,  of 
a  knowledge  of  its  details.  Success  in  Leveeing,  as  in  all  other 
matter  of  practice,  is  regulated  by  paying  due  regard  to  small 
particulars.  The  intention  of  this  contribution  to  the  sys- 
tematizing of  those  works  excludes  from  this  book  a  full 
examination  of  all  the  specialities  that  have  arisen  in  the  course 
of  my  experience  on  Levees  in  both  Mississippi  and  Arkansas. 
Particulars,  such  as  occur  often  or  involve  important  consider- 
ations, are  perhaps  not  excluded  by  the  general  plan  laid  down 
for  my  guidance  in  these  pages.  Attention  may,  therefore,  be 
directed  to  a  few  considerations  suggesting  themselves  by  the 
special  experience  of  my  Levee-works.  In  preparing  the 
ground  for  Levee-base  it  is  necessary  to  clear  and  grub  the 
whole  thoroughly,  leaving  neither  stump,  root,  brush,  weed,  nor 
even  grass.  This  important  duty  is  generally  done  with  great 
carelessness.  Before  the  work  of  embankment  is  commenced, 
all  the  timber,  roots,  weeds,  and  grass  removed  from  the  foun- 
dation ought  to  be  disposed  of  in  piles  and  burned  to  ashes. 
This  rule  should  be  enforced  rigidly.  It  is  the  only  means  of 
guaranteeing  the  exclusion  of  all  unfit  material  from  the  body 
of  the  Levee.  In  Arkansas  particularly,  and  in  Mississippi  to 
a  very  large  extent,  to  place  logs,  brush,  and  even  whole  trees, 
in  the  body  of  a  Levee  was  an  impropriety  of  not  exceptional 


80  PRINCIPLES   AND    PRACTICE   OF 

but  of  common  occurrence.  *  In  new  Levees  such  an  imposition 
can  always  be  detected  after  rains  by  vertical  holes  in  the 
crown  and  sides  ;  and  in  dry  weather  may  be  detected  by 
piercing  the  Levee  at  intervals  along  the  crown  with  an  iron  rod. 
The  only  certain  means,  however,  of  excluding  from  the  Mis- 
sissippi embankments  the  materials  grubbed  and  cleared  from 
their  base,  is  the  enforcement  of  the  rule  that  those  materials 
shall  have  been  burned  in  the  presence  of  the  superintendent 
before  the  bank  shall  be  commenced. 

In  connection  with  this  subject  it  may  be  observed  here, 
that  the  clearing  along  the  line  of  Levee  ought  to  extend  to  all 
trees  growing  within  their  own  respective  lengths  on  either 
side  of  the  crown  of  the  Levee.  All  trees  without  that  distance 
ought  to  be  cut  dawn  ;  but  if  this  should  be  supposed  a  need- 

*  The  Coahoma  Commissioner — who  has  made  himself  thoroughly  conversant 
with  the  scientific  principles  and  practical  facts  of  Levees — in  bearing  testimony  to 
the  triumphant  success  during  the  late  extraordinary  flood  of  Levees  properly 
planned  and  executed,  calls  attention  to  the  cause  of  breaks  being  Logs,  &c.,  in  the 
bank.  In  his  printed  Address,  of  the  25th  last  July,  that  gentleman  holds  the  fol- 
lowing language: — "The  question,  then,  is:  did  the  Levee  when  properly  built  per- 
form the  work  for  which  it  was  declared  competent  1  I  say  it  did ;  and  challenge 
any  man  upon  the  whole  line  of  Levee,  on  either  side,  to  point  to  a  single  break  where 
there  did  not  exist  a  local  cause."  The  address  goes  on  to  say : — "  But  in  the  large 
majority  of  cases  where  breaks  occurred,  the  water  either  ran  over  the  top,  or 
stumps  and  logs  embedded  in  the  work  occasioned  the  break." 

One  of  the  most  general  causes,  however,  of  Levee-breaks  during  the  late  floods, 
has  been  the  Craw-fish.  This  animal  digs  a  hole  through  the  Levee,  from  the  water 
side,  in  order  to  obtain  a  passage  through — the  small  fish,  or  water  insects  passing 
in  with  the  flow,  furnishing  the  object  and  the  reward  of  his  labor  as  prey.  In  sand, 
the  Craw-fish  cannot  carry  out  his  purpose,  for  the  hole  when  made  falls  in,  the 
Craw-fish,  accordingly,  desisting  in  his  work.  Clay  banks  are  well  adapted  for  the 
operations  of  the  Craw-fish,  and  though,  essentially  the  best  in  all  other  particulars 
for  Levees,  are  open  to  this  grave  objection ;  this  fact  suggests  that  to  obtain  the 
general  advantages  of  clay  embankments  in  Leveeing,  it  is  expedient  in  order  to 
guard  against  its  special  disadvantages  in  those  works,  to  carry  up  within  them  a 
wall  of  sand.  The  experience  of  the  late  flood  makes  this  sand-wall  in  clay  Levees 
a  detail  of  the  first  importance. 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  81 

less  precaution,  it  certainly  is  not  so  in  the  case  of  all  such 
trees  leaning  in  the  direction  of  the  Levee.  This  should  be 
done  during  the  clearing  of  the  ground  for  the  Levee,  the 
trunks  to  be  burned  with  the  rest  of  the  clearing-spoil.  During 
high-water  the  falling  of  a  tree,  from  either  side,  across  the 
embankment,  will  cut  down  through  the  crown  at  least  several 
feet.  I  have  known  one  instance  where  a  large  cotton-wood 
(4J  feet  in  diameter)  cut  a  5J  feet  Levee  to  its  base.  If  a  simi- 
lar cut  should  occur  during  the  flood  season,  on  a  high  Levee, 
the  water  admitted  through  the  gap  so  made  would  form  a 
crevasse,  sweeping  away  large  lengths  of  the  Levee,  inundating 
the  adjoining  plantations,  and  for  the  season  of  its  occurrence, 
destroying  the  object  of  the  whole  system  of  Leveeing  to  the 
people  and  property  of  hundreds  of  square  miles.  But,  besides 
the  avoidance  of  this  danger,  the  removal  of  those  leaning 
trees,  at  first,  is  in  fact  less  expensive  than  when  they  have 
fallen. 

Road-crossings  are  very  frequently  cut  across  Levees,  in 
Mississippi,  and  elsewhere,  during  low-water.  The  planter 
immediately  concerned  is  expected  to  see,  at  the  proper  time, 
that  such  a  cut  is  duly  filled  ;  but  in  some  stretches  of  Levee, 
it  often  occurs  that  what  is  every  body's  business  is  no  body's. 
Besides,  this  liberty  with  the  Levee  is  bad  in  principle  ;  for 
it  points  directly  to  impunity,  for  infringements  on  the  sanc- 
tity— so  to  speak — of  the  work  in  less  dangerous  particulars. 
Rows  of  Osage-Orange,  or  other  hedge-shrub  set  along  the  base 
of  each  slope,  will  save  the  embankment,  better  than  all  the 
restrictions  of  law,  from  injury  by  either  manor  beast.  In  the 
absence  of  these  hedges,  however,  it  may  be  suggested  that, 
to  guard  against  the  cutting  of  roads  across  the  Levee,  the 
best  course  would  be,  as  in  Holland,  to  raise  the  natural  surface 
of  the  road-way  by  embankment  from  each  side  in  easy  slopes, 
to  the  top  of  the  Levee.  To  slope  down  the  Levee-level  at  a 

rate  of  even  20  to  1  to  the  level  of  the  road  on  either  side 

6 


82  PRINCIPLES   AND    PRACTICE   OP 

crossing  it,  will,  in  general,  require  comparatively  little  work, 
the  ba&e  of  such  an  extra  bank,  exclusive  of  one-half  the  base 
of  the  Levee,  being  for  crossing  a  Levee  of  10  feet  high,  but  in 
all  some  370  feet.  This  road-way  is,  in  Holland,  termed  "  Ramp." 
The  cost  of  this  extra  work  is  but  small  for  securing  the  advan- 
tage of  placing  the  continuity  of  the  Levee  beyond  the  acci- 
dents of  local  carelessness — of  placing  the  important  principle 
of  its  inviolability  beyond  the  infringement  of  popular  necessity. 

Levees  across  creeks  or  bayous  are  very  often  made  wide 
enough  on  top  to  constitute  a  roadway.  The  inviolability 
of  the  Levee  comes  in  here  again  to  object  as  an  important 
principle  against  this  practice.  Besides  that  the  course  is 
objectionable  on  the  ground  of  economy.  The  grassing  of  the 
crown  as  a  saving  of  wear  and  tear  is,  with  the  supposition  of 
the  roadway,  out  of  the  question.  If  cattle-trespass  on  the 
slopes  is  to  be  excluded,  it  can  be  excluded  with  a  roadway  on 
the  top  by  only  the  cost  of  four  instead  of  two  rows  of  hedges, 
two  on  each  side  of  the  roadway  and  two  along  each  slope. 
The  wear  and  tear  of  the  whole  Levee  with  the  rut-cuttings  of 
wheels  in  wet  weather,  and  the  slope-breakings  of  horse-hoofs 
in  wet  and  dry  weather,  would  make  this  roadway  tell  heavily 
on  the  Levee-account  in  increased  outlays  for  maintenance. 
These  objections  apply  with  equal  force  to  employment  of 
Levees  for  roadways,  whether  along  their  whole  length  or  for 
any  part  of  that  length.  In  the  case  of  bayou  crossings,  or 
the  crossings  of  other  deep  breaks  in  the  general  surface  of 
the  back-land,  the  roadway  may  be  combined  with  the  Levee 
without  going  to  the  extent  of  making  them  perfectly  identi- 
cal. The  following  section  shows  a  method  of  combining  the 
roadway  with  the  Levee  at  deep-crossings  with,  in  general, 
less  work — a  method,  too,  removed  from  the  objections  urged 
above  against  using  the  crown  of  the  Levee  for  the  purpose. 

The  Levee  here  is  assumed  to  be  protected  fully  from  tres- 
passers by  the  hedge-rows  shown  at  a  and  6,  the  whole  surface 


EMBANKING   LANDS   FROM    RIVER-FLOODS. 


intermediate  between  these  being  protected   by  the  proper 
coating  of  grass.     The  roadway,  of  course,  is  situated  on  the 
dry  side,  and  as  an  extra  to  the  Levee,  may  be  left  to  the  par- 
ties concerned  in  it  as  a  road  for  its  maintenance.     Three- 
fourths  of  it  may  be  washed  or  worn  away  without  any  incon- 
venience  to   the  Levee.     Improvements  of  this  sort  on  the 
present  practice  must  be  regarded  with  the  consideration  due 
to  everything  pointing  to  a  saving  in  public  outlay — in  taxation. 
The  general  question  of  making  Levees  the  site  of  the  road- 
ways required  for  the  traffic  and  travel  taking  their  direction, 
is  met   in  the  foregoing  remarks  on   Levee    roadways.     The 
gravest  objection,  as  has  been  seen,  applies  to  the  location  of 
roads  on  drainage  embankments.     Occasional  travel  even  is  so 
injurious   that  it  ought  to  be  avoided  by  all   means — where 
more  efficient  means  are  not  employed  by  the  collection  of 
brush,  briars,  or  other  obstacles  across  the  whole  extent  of  the 
bank  at  intervals.     These  impediments  are  absolutely  essential 
in  new  works  on  new  locations  ;  for  few  men  will  be  so  scru- 
pulously observant  of  law  as  to  ride  through  the  tangled  paths 
of  a  swamp  when  they  may  choose,  in  their  stead,  the  open  and 
unbroken  smoothness  of  a  Levee.     The  enforcement  of  penal- 
ties, under  such  circumstances,  is  difficult.    The  best  remedy  in 
all  such  cases,  after  that  of  impervious  hedge-rows,  is — and  for 
travel  and  traffic  only,  it  is  a  perfect  remedy — the  construction 
of  a  roadway  within  the  Levee  at  a  distance  sufficient  to  save  the 
berm  from  the  contingency  of  encroachment  by  either  hoof  or 
tyre.     This,  with  brush  walls  drawn  across  the  bank  at  inter- 
vals, will  save  the  Levee  from  all  damage  except  that  arising 
from  the  trampings  of  cattle  and  the  "  rooting'7  of  hogs.     The 
Osage-Orange,  however,   is  infinitely  better  than  an  army  of 
police  and  a  volume  of  penal  laws,  for  the  protection  of  em- 
bankments from  all  trespass. 


84  PRINCIPLES   AND   PRACTICE   OP 

Excavations  of  the  ground  outside  a  Levee  is  objectionable. 
In  sandy  or  other  weak  earths  it  is  even  worse  so  than  in  clays. 
Under  any  circumstances  such  cuts  ought  to  be  removed  as 
far  as  possible  from  the  berm  of  the  Levee  ;  but  never  less 
than  ten  feet.  The  "  pits"  dug  in  such  positions  ought  not  to 
be  continuous  ;  but  ought  to  be  divided  from  each  other  by 
walls  preserving  the  continuity  of  the  natural  surface.  Separ- 
ated thus  from  each  other,  those  excavations  will  fill  up  the 
sooner  under  the  depositions  of  floods.  These  breaks  in  the 
external  cuts  will  also  prevent  them  of  becoming  channels  of 
flow  ;  and  thus  guard  against  the  creation  of  avoidable  current 
washes  on  the  slope  and  berm  of  the  embankment.  The  slope 
of  those  external  pits  should,  on  the  side  next  the  toe  of  the 
Levee,  never  be  vertical,  but  always  dressed  off  at  an  angle 
fully  equal  to  that  of  the  adjoining  Levee  slope.  Left  at  a 
less  slope,  the  pit-banks  may  fall  in,  and  the  falling  so  occurring 
will  then  advance  until  finally  it  shall  have  undermined  at 
least  a  portion  of  the  Levee  itself.  Trifling  as  this  detail  may 
appear,  it  is  urged  here  as  one  which  practical  experience  has 
pointed  out  as  of  great  importance.  Exterior  excavations, 
then,  for  the  construction  of  Levees  should  be  made  in  pits 
separated  from  each  other  at  intervals  by  walls,  the  inner 
slopes  of  these  pits  being  never  nearer  the  Levee  base  than  ten 
feet,  and  never  of  a  more  rapid  angle  than  that  of  the  water- 
slope  of  the  adjoining  Levee.  These  precautions  ought  to  be 
laid  down  expressly  in  Levee-contracts.  Carried  out  practically 
they  will  save  the  work  from  the  contingencies  of  its  first  and 
perhaps  second  year  of  trial ;  but  after  that,  the  foreshore — 
the  ground  outside  the  Levee — will  "  warp"  or  "  silt  up"  under 
the  flood-deposits  until  the  resulting  elevation  going  on  to  the 
full  height  of  high  water  mark,  the  foreshore  side  of  the  em- 
bankment will  cost  little  or  nothing  for  maintenance. 

Large  Levees  require  in  their  construction  especial  care. 
As  a  general  rule  it  may  be  observed  of  those  works  that  the 


EMBANKING   LANDS    FROM   RIVER-FLOODS.  85 

heavier  they  are  the  weaker  is  their  natural  foundation.  The 
twenty  or  thirty  feet  Levee  in  all  cases  within  my  observation 
implied  a  Levee,  whether  across  swamp,  bayou,  or  "  old  bed," 
having  for  its  base  a  soil  no  stronger  than  shifting  sands  or 
watery  puddle.  All  such  Levees,  on  this  consideration  and  on 
the  further  consideration  of  proper  compactness  and  strength, 
ought  to  be  carried  up  in  regular  layers  of  earth,  each  layer 
"  dished''  out  from  the  centre  and  tramped  over  by  the  hauling 
necessary  for  the  next  succeeding  layer.  These  layers  should 
not  exceed  three  feet  in  thickness.  Crusts  thus  carried  up 
one  after  another  from  the  base,  assist  to  distribute  the  press- 
ure of  the  whole  equally  over  the  whole  base  ;  and  thus  in  the 
case  of  weak  foundations  assist  largely  in  the  stability  of  the 
work.  Hollowed  out  from  the  centre — "  dished" — these  layers 
or  crusts  of  tramped  earth  fitting  each  into  the  one  below  it 
cannot  shift  under  the  lateral  strain  of  high-water.  After  en- 
suring safety  at  first  by  carrying  the  bank  up  thus  in  layers, 
the  whole  becomes  subsequently  one  solid  and  settled  mass. 
The  settlement  allowance  in  banks  so  constructed  is  merely 
nominal.  In  connection  with  the  stability  of  Levees  across 
ow£-discharging  bayous,  it  may  be  observed  here,  that  that 
stability  is  sometimes  threatened,  after  all  proper  precaution 
in  construction,  by  the  accumulation  of  water  on  their  inner 
side.  The  bayou  having  discharged  outwards  a  mere  trickle 
perhaps  at  the  time  of  stopping  it,  soon  accumulates  to  a  con- 
siderable body  of  water,  until  finally  the  whole  becomes 
ponded  up  against  the  sides  and  bottom  of  the  bayou  and  the 
inside  slope  of  the  Levee  to  the  height  of  the  bayou  bank. 
The  additional  load  on  the  foundation  over  and  above  the 
Levee  and  the  river  flood-water,  is  in  itself  objectionable, 
though  perhaps  not  quite  so  much  so  as  might  appear  at  first, 
when  it  is  recollected  that  the  distribution  of  the  weight,  front 
and  rear  of  the  Levee,  would  save  the  danger  of  "  bulgings" 
up  at  the  toe  of  the  Levee — the  place  of  these  bulgings  being 


86  PRINCIPLES   AND    PRACTICE   OP 

always  occupied  by  corresponding  sinkings  of  the  embank- 
ment. But  the  greatest  objection  of  such  pondings  up  is  their 
continuance  ;  seeing  that  the  longer  they  continue  the  more 
thorough  and  the  deeper  is  the  saturation  of  the  underlying 
earths  ;  and  the  more  thorough  and  deeper  their  saturation 
the  greater  the  extent  and  the  degree  of  the  weakness  or 
"  meltings"  of  the  earths  in  the  foundation  of  the  Levee.  In 
order  to  guard  against  this  evil,  it  is  necessary  that  small  cuts 
be  run  up  through,  or  out  of,  such  bayous  to  such  a  point  as 
may  be  necessary  to  divert  their  drainage  into  the  general  out- 
fall of  the  surrounding  country.  All  Levees  across  ottf-flow 
creeks  or  bayous  have  been  observed,  when  this  precaution 
has  been  neglected,  to  sink  into  their  foundations  ;  and  as  a 
consequence  to  cost  more  than  otherwise  for  their  maintenance. 
Crusts  of  earth  have  been  referred  to  already  as  means  for 
the  distribution  over  a  wide  surface,  of  superincumbent  loads. 
In  the  case  of  a  "  muck  ditch  ."  cut  along  the  site  of  the  Great 
Yazoo  Pass-Levee  of  1855 — cut  against  the  express  direction, 
if  memory  serve  me  truly,  of  the  Commissioner  and  the  Engi- 
neer— the  advantage  of  an  unbroken  crust  of  this  sort  was 
illustrated  very  strikingly.  The  division  by  the  "  muck  ditch" 
having  taken  place  under  the  line  of  greatest  load,  that  load, 
pressing  on  the  lips  of  the  cut  vertically,  acted  on  them  as  re- 
marked in  such  cases  on  a  previous  page,  with  a  leverage,  until 
driven  down  step  by  step  the  crust  must  have  become,  by  the 
consequent  bending,  broken  near  the  toe  of  the  Levee  on  each 
side.  Two  distinct  pieces  of  crust  were  thus,  in  all  probability, 
driven  down  angularly  into  the  thin  matter  underneath  ;  and 
thus,  instead  of  using  every  precaution  to  preserve  the  natural 
crust  as  a  grillage  under  the  bank,  the  Levee  was  left  to  seek 
its  foundation  as  best  it  might  amongst  quicksands  and  fluid 
puddle.  The  weakness  of  the  foundation  told  itself  accord 
ingly  by  not  only  the  sinking  of  the  crown  of  the  embankment, 
but  also  by  the  bulgings  of  the  slopes  and  the  spreading  of  the 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  87 

base — "  a  corduroy  "  or  causeway  of  logs  near  the  inner  talus 
having  been  forced  by  those  spreadings  from  a  straight  line 
into  a  succession  of  zig-zags.  Alarmed  by  the  sinkage  of  his 
work — a  sinkage  that,  according  to  his  estimate,  was  made 
naturally  enough  by  one  in  such  a  position,  to  cover  all  the  losses 
consequent  on  his  own  mismanagement — the  contractor  became 
unmanagable.  The  Engineer  recommended  him  to  open  a 
ditch  of  a  few  feet  wide  and  of  five  or  six  feet  deep  inside  and 
parallel  with  the  Levee,  in  order,  by  filling  up  the  same  with 
the  trunks  of  the  young  cotton-woods  cleared  from  the  base  of 
the  Levee,  to  present  a  breast  work  of  equally  bearing  resistance 
on  the  dry  side  to  the  spreadings  of  the  base — the  then-standing 
flood-waters  on  the  wet  side  offering  sufficient  resistance  to 
spreadings  or  bulgings  on  the  wet  side.  A  deep  pit  of  sand 
furnished  convenient  drainage  for  the  ditch  so  suggested  ;  and 
the  excavations  of  the  ditch  would  have  been  available  for  the 
completion  of  the  embankment  according  to  the  contract. 
Instead  of  adopting  this  course,  howrever,  the  contractor  at- 
tempted to  carry  up  the  sinking  Levee  to  the  contract-height 
by  removing  the  masses  of  earth  bulged  out  on  its  sides  and 
spread  out  beyond  its  base  to  the  crown,  heedless  of  the  re- 
monstrance of  the  Engineer  that  in  doing  so  he  was  merely 
revolving  an  endless  chain.  Every  yard  taken  from  the 
bulgings  on  the  side  and  removed  to  the  sinkings  on  the  top, 
was  speedily  replaced  by  another  yard  on  the  sides,  the  top 
remaining  in  statu  quo.  Finally,  however,  the  work  was  re- 
sumed at  the  base  and  carried  up  in  closer  conformity  with  the 
slopes  ;  and,  all  parts  of  the  cross-section  thus  newly  loaded,  the 
crown  carried  up  finally  in  "  a  comb"  to  exclude  the  flood  then 
standing  some  20  feet  on  the  water-slope,  the  whole  presented 
sufficient  solidity,  under  all  the  unfavorable  circumstances  that 
attended  its  construction,  to  have  dammed  back  that  year's 
flood.  This  case  fell  within  the  practice  of  Mr.  M.  B.  Hewson. 
Another  case  of  weak  foundation  for  a  Levee  came  under  the 


88  PRINCIPLES   AND   PRACTICE   OP 

observation  of  that  gentleman  in  the  construction  of  the  great 
Levee  across  the  mouth  of  the  Old  Lake  of  Oldtown,  in  the 
State  of  Arkansas.  The  site  of  this  Levee  had,  within  the 
memory  of  men  living  in  the  neighborhood,  been  the  bed 
of  the  Mississippi  River  ;  and  as  such  may  be  well  supposed  to 
have  presented  a  foundation  of  a  description  the  very  weakest. 
A  shallow  stream  running  across  the  proposed  line  of  work,  the 
undertaking  had  not  the  advantage  in  some  places  of  even  the 
hard  crust  of  the  Yazoo  Pass.  The  irregular  course  pursued  in 
carrying  out  those  works  on  the  Mississippi  confines  generally 
its  restriction  on  the  contractor  to  the  height,  width  at  base, 
and  width  of  crown,  the  means  by  which  he  fulfills  those  con- 
ditions being  questions  for  only  his  consideration.  Acting  on 
the  part  of  the  State,  Mr.  Hewson  had  no  voice  as  to  foundation 
or  any  other  obvious  preliminary  in  a  proper  construction  of 
the  work.  The  contractor  accordingly  dumped  in  his  earth 
without  any  preparation  of  the  foundation  ;  and  counting  on 
pay  for  every  yard  so  dumped,  carried  up  the  work  by,  simply f 
force  of  purpose  and  labor.  The  centre  frequently  sank  into  the 
foundation.  Standing  sometimes  for  a  couple  of  hours  at  its 
full  height,  it  would  drop  down  suddenly  from  5  to  10  feet.  The 
base  spread  to  an  incredible  extent  at  all  points  but  one — that 
one  being  loaded  heavily  with  an  interlocked  and  tangled  mass 
of  logs,  branches,  and  trunks,  removed  in  clearing  the  site  of 
the  work.  The  spreadings  having  reached  their  utmost  at  all 
other  points,  the  work  was  being  carried  up  along  the  loaded 
length  of  the  slope,  when  suddenly  the  tangled  mass  of  timber 
loading  it  was  torn  asunder  with  a  loud  noise,  and  shot  for  some 
distance  from  its  original  position.  The  bulging  that  took  the 
place  of  this  weight  on  the  base  of  the  Levee  was  found  by 
measurement  to  have  been  some  4000  yards !  Such  are  the 
forces  exerted  by  such  Levees  ;  and  such  the  character  of  their 
foundations.  The  "  sinkage,"  as  it  is  locally  termed,  was,  how- 
ever, in  the  case  of  the  Yazoo  Pass-Levee,  a  mere  trifle  in  com- 
parison with  that  at  Oldtown. 


EMBANKING   LANDS  FROM   RIVER-FLOODS.  89 

Weak  foundations  occur  in  the  case  of  Levees,  in  only  the 
cases  of  those  important  works  that  may  be  considered  the 
Keys  of  the  whole.  The  Yazoo  Pass  embankment  once  swept 
away,  the  whole  extent  of  Levee  remaining  in  the  County  of 
Coahoma  would  become,  virtually,  valueless  to  the  parties 
living  behind  it  as  a  protection  from  inundation.  The  under- 
taking of  the  Levee-system  at  all,  involves,  therefore,  the 
necessity  that  all  those  more  important  points  of  the  system  be 
executed  in  a  manner  to  insure,  at  least,  as  high  a  degree  of  stabil- 
ity as  any  of  the  less  important  parts  of  the  system.  With  some 
30  feet  of  water  standing  on  its  outer  slope  at  flood-time,  its  inner 
slope  resting  on  the  bed  of  a  channel,  of  like  depth,  constitu- 
ting the  arterial  drain  of  the  back  country,  the  failure  of  one 
of  those  Key-works  of  the  system,  when  occurring  to  even  the 
smallest  extent,  involves  its  total  destruction.  The  rush  of 
water  through  the  whole  width  of  this  Key-levee,  under  a 
head  of  some  30  feet,  sweeps  into  the  back  country  in  a  foam- 
ing torrent ;  the  whole  system  of  back  drains  becoming,  in  the 
first  place,  suddenly  charged  to  the  lips  ;  and  then,  all  the 
overflow  passing  off  upon  a  surface  deprived  of  out-fall,  the ' 
country  behind  the  Levee  becomes,  to  a  greater  or  less  extent 
according  to  duration  of  the  flood-level  in  the  river,  com- 
pletely deluged.  On  the  other  hand,  a  "  crevasse,"  or  breach 
in  the  general  line  of  the  Levee,  may  not  only  be  stopped 
altogether  before  it  arrives  at  any  considerable  width  ;  but  at 
the  worst,  the  depth  of  its  out-flow  not  exceeding  a  few  feet, 
the  back  lands  pass  off  the  water,  through  their  system  of  back- 
drainage,  at  a  rate,  if  not  even  quite  as  rapid  as  the  in-flow, 
quite  rapidly  enough  in  the  generality  of  cases  to  prevent  the 
engorgement  of  the  back-drains  before  the  fall  of  the  river- 
level.  A  breach  in  the  Key-levees,  then,  involves  a  certainty 
of  wide  inundation  ;  while  a  breach  in  a  less  important  part  of 
the  system  leads  to  an  inundation  under  the  worst  circumstan- 
ces, limited  in  its  extent,  and  in  its  duration  brief.  But  this 


90  PRINCIPLES   AND   PRACTICE   OF 

is  not  the  only  reason  why  it  becomes  necessary  to  con- 
struct Key-levees  with  special  care.  Costing,  according  to 
their  present  mode  of  construction  at  a  rate  so  high,  in  some 
cases,  as  upwards  of  $60,000  a  mile,  whereas,  the  generality  of 
Levees  do  not  cost  over  $2,500  a  mile  ;  a  breach  in  one  of  those 
heavy  works — leading  as  it  always  does  to  its  total  demolition, 
results  in  a  very  serious  loss  of  money.  The  destruction  of 
Yazoo  Pass -Levee  was  as  great  an  injury  to  the  treasury  of 
Coahoma  County  as  would  have  been  the  destruction  of  the 
whole  embankment,  from  the  junction  with  the  Pass-levee  to 
a  point  as  far  South  as  Friar's  Point !  The  Commissioner  was 
very  much  censured  by  parties  interested  in  the  stability  of 
this  Pass-levee,  for  his  special  outlays  on  construction  of  this 
work,  and  for  his  rigid  enforcement  of  the  conditions  set  forth 
in  the  contract  for  securing  that  stability  •  but  how  thoroughly 
rebuked  his  short-sighted,  and,  perhaps,  factious  censurers 
must  have  felt,  when  they  discovered  to  their  cost,  by  the  des- 
truction, in  1855,  of  that  most  important  work,  that  in  all  his 
care  and  all  his  "  harshness,"  Col.  Alcorn  was  pursuing  the 
course  as  a  public  servant,  of  courageous  honesty  and  enlight- 
ened carefulness.  The  truth  is,  Col.  Alcorn  felt  at  the  time, 
that  his  duty  in  the  case  of  the  Pass-levee  was  rather  under- 
done than  overdone  ;  and  in  conversation  with  Mr.  M.  B. 
Hewson,  on  the  subject,  frequently  referred  to  the  embarrass- 
ment in  which  he  was  placed  in  the  case,  by  the  absence  of  a 
sound  and  intelligent  public  opinion  as  to  the  conduct  of  those 
works.  The  purse-strings  being  in  the  hands  of  the  tax-payers 
in  the  case  of  Levees,  it  is  of  importance  to  their  best  interests 
to  place  such  measures  as  are  necessary  for  the  proper  con- 
struction of  those  works,  under  the  endorsement  of  their 
understandings.  Having  with  this  view  referred  to  the  special 
importance  of  such  works  as  the  Yazoo  Pass-Levee,  and  the 
Old  Town-Levee,  &c.,  it  is  proposed,  now,  to  offer  some  general 
remarks  on  Levee-foundations. 


EMBANKING   LANDS   FROM   RIVER-FLOODS.  91 

The  more  important  portions  of  the  system  of  river-embank- 
ment in  the  case  of  the  Mississippi,  rests,  as  has  been  said,  on 
foundations  of  puddle  or  quicksand.  Continuing  to  dump  in 
earth  into  embankments  ~on  such  a  foundation,  is  found  in 
practice  to  result,  after  a  greater  or  less  waste  of  earth,  in 
compressing  the  foundation  downwards  and  outwards  to  a 
compactness  sufficient  for  the  resistance  necessary  to  sustain 
the  intended  Levee.  The  Levee  accordingly  stands — its  height, 
crown,  and  side-slopes  being  in  perfect  accordance  with  the 
contract.  This  is  all  the  public  expect  ;  and  unfortunately, 
with  their  present  views,  this  is  all  they  will  sustain  their 
Commissioner  in  enforcing.  The  flood,  however,  rises  on  the 
face  of  this  Levee — 10  feet,  15  feet,  20  feet — even  25  feet,  and 
a  load  of  600  Ibs.,  900  Ibs.,  1500  Ibs.  becomes  thus  added  to 
every  square  foot  of  the  outer  half  of  the  Levee  base  ;  while 
no  corresponding  weight  on  the  inside  is  available  for  estab- 
lishing a  counterpoise  in  the  watery  material  of  the  foundation. 
The  compression  that  the  foundation  underwent,  originally, 
before  the  Levee  attained  the  required  height,  was  the  result 
of  the  weight  of  the  earth  employed  in  its  construction  ;  and 
it  is  only  reasonable  to  infer  that,  with  the  same  foundation,  a 
further  load,  whether  of  earth  or  of  water,  will  occasion  a  fur- 
ther compression.  Additional  sinking,  or  "  canting"  under  the 
outside  slope,  and  additional  bulging,  or  spreading  of  the  inside 
slope,  is  a  natural  result  under  such  circumstances  ;  and  the 
special  weakening  of  foundation  under  the  special  saturation 
of  a  superincumbent  head  of  water,  combining  with  the  other 
natural  result  in  the  case,  no  surprise  ought  to  be  felt  that  the 
great  Levees,  constructed  after  the  general  practice  on  the 
Mississippi,  should  be  swept  away  before  high  floods.  To  con- 
struct those  works  properly,  then,  requires  special  steps  in 
reference  to  the  strength  of  their  foundations.  Brush  makes  a 
very  good  foundation  in  weak  soils.  McAdamized  Roads  have 
been  carried  through  otherwise  impassable  marshes  in  England, 


92  PRINCIPLES   AND    PRACTICE   OP 

on  foundations  of  brush  laid  in  considerable  thickness  upon 
the  surface  of  the  marsh.  It  is  extensively  used  in  Holland, 
and  the  "  Low  Countries,"  to  strengthen  the  foundation  of 
heavier  embankments  than  are  likely  ever  to  occur  in  practice 
upon  the  Mississippi  bottom.  In  Ireland,  heavy  embankments 
of  the  Grand  Canal,  and  also,  embankments  of  the  Great  West- 
ern Railroad  have  been  carried  in  several  instances  across  deep 
"  flow-bogs"  on  brush.  The  Grand  Trunk  Railroad,  of  Canada, 
has  a  bank  some  thirty  or  forty  feet  high,  across  a  deep  and 
wide  marsh,  sustained  by  a  brush  foundation.  Several  such 
instances  of  the  use  of  brush  might  be  mentioned  here,  to  show 
how  useful  for  the  purpose  of  Levee-foundations  is  a  material 
that,  along  the  banks  of  the  Mississippi,  may  be  obtained  with- 
out stint  or  trouble.  The  branches  of  the  trees  cut  off  for  the 
purpose,  should  be  laid  evenly  across  the  base  of  the  Levee,  in 
layers  24  inches  thick,  the  direction  of  those  in  each  layer  "  ang- 
ling" across  the  line  of  the  base,  those  of  the  layer  next  above 
being  laid  "  angling"  in  the  other  direction.  Two  layers  are  quite 
sufficient  for  ordinary  heights  of  bank,  and  ordinary  weakness 
of  foundation  ;  but  in  other  cases,  it  were  better  to  lay  three 
layers  or  even  four.  "  Old  beds,"  such  as  the  Yazoo  Pass,  or 
Old  Town  Bayou,  should  in  all  cases  be  brushed. with  four  lay- 
ers, compressible  to  a  thickness  of,  at  least,  six  feet,  each  layer 
having  its  branches  laid  across  the  line  of  Levee,  askew — the 
second  layer  crossing  that  of  the  first,  and  so,  also,  with  the 
others.  The  brush  should  be  cut  off  regularly,  so  that  it  would 
never  extend  on  either  side  within  ten  or  twelve  feet  of  the 
toe  of  the  bank ;  pressed  for  even  its  own  thickness  into  the 
foundation,  and  the  brush  covered  up  completely,  the  embank- 
ment resting  upon  it  will  not,  necessarily,  be  open  to  the 
objection  of  leakage.  Brushing,  properly  and  carefully  em- 
ployed, in  even  the  highly  unfavorable  circumstances  of  the 
Key-works  of  the  Levee-drainage,  will  constitue  a  perfectly 
stable  foundation.  Fascines  are  sometimes  employed  in  the 


EMBANKING   LANDS   FKOM   RIVER-FLOODS.  93 

foundations  of  embankments  ;  but,  while  much  more  trouble- 
some, are  not  so  efficient  as  simple  brushing  executed  properly. 
Fascines  may  be  described  as  small  bundles  of  brush,  each  tied 
firmly  like  a  birch-broom.  These  are  laid  down  one  row  across 
the  other  for  foundations  of  banks  ;  but  all  the  advantages  of 
their  compactness  may  be  secured  in  brushing,  by  selecting 
the  brush  carefully  in  the  first  instance — long,  straight,  tough, 
and  sufficiently  light — and  in  the  next  instance,  pinning  it 
down  occasionally  by  wooden  forks  to  the  ground  in  the  first 
case,  and  to  the  layer  below  it,  in  the  next.  More  perfect 
continuity  latterally  and  longitudinally  may  be  obtained  with 
the  simple  brush  than  with  the  fascines.  Sand  is  another 
material  most  available  along  the  Mississippi,  for  the  purposes 
of  artificial  foundations.  Loose  in  its  parts  as  it  is,  sand  is 
not  supposed,  generally,  to  be  capable  of  constructing  a  mass 
of  such  stiffness  as  to  distribute  over  its  length  and  breadth 
the  pressure  of  a  heavy  load*  This,  however,  is  the  fact.  Like 
water  in  other  particulars,  it  is  especially  like  water  in  dis- 
charging its  pressures,  under  certain  circumstances,  latterally 
as  well  as  vertically.  This  property  of  sand  has  lead  to  its 
employment  in  foundations  as  a  substitute,  in  certain  cases, 
for  piles  of  wood  and  of  iron.  Wooden  piles  obtain  their  bear- 
ing mainly  from  the  resistance  presented  to  their  section  ;  but 
sand-piles,  in  addition  to  this  resistance,  are  found  also  to 
present  a  further  resistance  along  their  sides.  Friction  or 
adhesion,  as  it  may  be,  this  increased  sustaining  power  of  the 
sand-pile  has  been  found  highly  useful  in  the  preparation  of 
foundations  for  heavy  Engineering  works  in  soft  and  deep 
alluvium.  Where  the  base  is  not  so  weak  as  to  require  the 
use  of  piles,  artificial  foundations  of  ample  strength  are  some- 
times obtained  by  spreading  over  the  natural  surface  a  thick 
and  uniform  coating  of  sand.  In  wet  situations,  however, 
hydraulic  lime  is  sometimes  added  under  this  practice  to  the 
extent  of  one-seventh  the  bulk  of  the  sand  ;  and  as  such  an 


94  PRINCIPLES   AXD    PRACTICE    OF 

addition  would,  in  all  likelihood,  be  found  necessary  in  the  case 
of  the  great  embankments  of  the  Levee-system,  the  use  of  sand 
for  artificial  foundations  for  Levees,  must,  on  the  score  of  econ- 
omy, be  confined  to  piling.  Brush,  however,  is  in  all  cases 
the  best  material  available  along  the  Mississippi,  for  the  pre- 
paration of  a  Levee-base  ;  but  before  .loading  an  unusually 
weak  base  with  an  unusually  heavy  embankment,  it  would  be 
well,  in  addition  to  the  brushing,  to  sink  one  row  of  sand-piles 
immediately  under  the  intended  site  of  the  crown,  and  two 
other  rows  on  each  side  of  it,  the  piles  in  each  row  alternating' 
regularly  with  those  next  it,  thus  : 


These  piles  ought  to  be  about  from  1  to  2  feet  in  diameter, 
the  centre  row  being  placed  at  intervals  from  centre  to  centre 
of  say  six  feet,  the  next  row  on  each  side  being  parallel  with 
this  centre  row  at  a  distance  from  it — from  centre  to  centre — 
of  about  8  feet,  the  intervals  between  the  piles  of  those  second 
rows  being  from  centre  to  centre  8  feet.  The  outside  piles 
ought  to  be  sunk  at  a  distance  from  each  other  and  from  the 
adjoining  rows  of  10  feet  from  centre  to  centre.  These  piles 
may  be  put  in  by  several  methods.  A  light  lift-ram  being  em- 
ployed to  drive  into  the  intended  place  (where  .the  same  may 
not  be  done  by  a  heavy  sledge)  a  Avooden  pile  of  the  intended 
size,  this  pile,  after  being  thus  sunk  to  the  required  depth,  must 
be  withdrawn,  and  the  hole  filled  in  rapidly  with  sand  for  the 
purpose,  this  sand-filling  being  compressed  at  intervals  as  it 


EMBANKING   LANDS  FROM   RIVER-FLOODS.  95 

progresses,  by  blows  of  a  rammer.  By  the  time  this  sand  pile 
is  thus  filled  in  and  compressed,  the  driving-party  will  have 
been  placed  ready  for  work  at  an  adjoining  pile  ;  and  thus  the 
whole  area  will  be  piled,  each  pile  being  completed  before  the 
driving  shall  have  been  commenced  for  that  adjoining  it.  Six 
or  seven  feet  is  quite  sufficient  as  a  depth  for  those  sand-columns. 
The  best  method,  however,  for  sinking  those  piles  where  the 
extent  of  the  work  would  justify  the  outlay,  would  be  by  an  iron 
cylinder,  furnished  on  the  inside  with  screw  threads  one-half 
the  diameter  in  width  ;  for  this  might  be  sunk  and  raised 
without  machinery  ;  and  permitting  conveniently  of  increased 
size,  is  well  adapted  to  piling  with  sand  columns  of  two  feet  in 
diameter.  The  larger  and  the  closer  the  sand  piles  the  more 
thoroughly  do  they  pack  the  material  of  the  base,  and  the  more 
effectively  do  they  increase  their  own  bearing-strength.  The 
regular  mode  for  sand  piling  is  that  pointed  out  here  ;  but  the 
rough  mode  of  doing  every  thing  in  Leveeing  will  probably 
substitute,  in  sinking  those  piles,  a  pole  forced  into  the  ground 
by  manual  strength,  and,  in  withdrawing  it  afterwards,  worked 
around  its  point  until  the  hole  becomes  sufficiently  widened. 
The  bottom  of  the  pile,  it  must  be  recollected,  will  be  very  small 
under  this  proceeding  ;  but  by  ramming  the  sand  thoroughly 
into  the  hole — water  or  no  water — sand-piles  will,  under  even 
such  poor  construction,  assist  largely  in  compressing  the  soft 
earth  around  them,  and  in  supporting  the  load  of  a  heavy  em- 
bankment. Be  the  mode  of  construction  for  those  piles  then 
what  it  may,  they  are  recommended  in  all  cases  of  unusually 
heavy  embankments  and  unusually  weak  earth  ;  and  when  even 
partially  employed  are  highly  valuable  accessions  to  "  brushing  " 
in  artificial  foundations.  The  popular  understanding  must,  how- 
ever, be  satisfied  in  reference  to  every  reform  in  the  con- 
struction or  management  of  Levees  ;  and  as  the  association  of 
strength  with  a  "  foundation  of  sand  "  conflicts  with  all  the 
previously  formed  views  of  that  popular  understanding,  it  is 


96  PRINCIPLES  AND   PRACTICE   OP 

well  to  sustain  the  use  of  sand-piles — as  has  been  done  in  the 
case  of  the  recommendation  of  brushing — by  reference  to 
specific  practical  tests.  In  reference  to  the  general  fact  of 
sand  being  a  strengthener  of  weak  foundations,  it  may  be  ob- 
served that  it  has  been  employed  successfully  as  such,  under 
heavy  masses  of  masonry  at  Geneva  in  Switzerland,  at  Bayonne 
and  Paris  in  France,  in  India,  in  Surinam,  and  doubtless  in  many 
other  places  where  its  use  has  not  fallen  within  the  knowledge 
of  the  writer  of  this.  In  the  "  Annales  des  Fonts  et  Chausees  " 
— the  Reports  of  the  Board  of  Public  Works  of  France — for 
1835,  a  complete  account  of  the  use  of  sand  in  foundations  is 
published  ;  and  in  order  to  satisfy  the  sceptical  planter  as  to  the 
utility  of  that  material  in  foundations,  the  following  extract  is 
made  from  that  report  in  the  translation  of  a  professional  paper 
on  the  subject,  by  a  member  of  the  British  Corps  of  Royal 
Engineers.  "  On  a  very  soft  soil  nine  piles  about,  4  feet  three 
inches  long  and  8  inches  in  diameter,  and  distant  from  centre 
to  centre  about  16  inches,  were  driven  with  a  monkey  weighing 
about  2  cwt.  falling  from  a  height  of  3  feet  6  inches  ;  the 
driving  was  continued  till  the  piles  only  yielded  about  \  of  an 
inch  at  a  stroke  ;  upon  these  piles  a  load  of  20,000  Ibs.  was 
placed  and  the  settlement  amounted  to  about  one-fifth  of  an  inch. 
These  nine  piles  were  then  drawn  j  and  the  holes  in  the  soil 
filled  in  with  sand  ;  16  more  piles  were  driven  in  the  same  way 
so  as  to  occupy  a  space  of  6  feet  square  ;  the  ground  was  then 
well  rammed ;  and  a  mass  of  masonry  similar  to  that  in  the 
former  experiment  was  built  and  loaded  with  lead  as  before  : 

Under  a  weight  of  1050  Ibs.  the  settlement  was  1-25  inch. 
"      2100  Ibs.        "  "      2-25  inch. 

"      3150  Ibs.        "  "      8-25  inch. 

Which  increased  to  4-25  inch. 

Under  a  load  of  18  tons  the  settlement  was        1-5  inch. 
21  tons  made  no  sensible  change,  and  30  tons 
increased  the  settlement  about  1-50,   and 
after  a  month  the  total  amounted  to  3-5  inch. 


EMBANKING  LANDS   FROM  RIVER-FLOODS.  97 

A  wall  about  12  feet  deep  filled  up  with  silt  and  clay  ;  after 
having  removed  about  16  inches  of  soil  from  the  surface  the 
under  stratum  was  found  quite  soft,  a  Ram  penetrating  6 
inches  at  a  stroke.  To  harden  this  soil,  25  piles  were  driven 
about  4  feet  6  inches  long  each  ;  this  forced  the  soil  up  about 
16  inches  above  the  previous  level ;  the  driving  was  continued 
till  20  blows  of  a  Ram  weighing  2  cwt.  let  fall  from  a  height  of 
3  feet  only,  caused  a  pile  to  penetrate  about  4  inches,  which 
took  about  40  minutes'  work.  After  having  driven  all  the  25 
piles  and  levelled  their  heads,  they  were  loaded  as  follows  : 

12  tons  caused  a  settlement  of  about  1-20  inch. 
18  tons  "  "  1-10  inch. 

And  in  three  days  this  increased  to    1-5  inch. 

These  piles  were  then  drawn,  and  the  holes  filled  with  sand, 
which  was  well  rammed,  and  which  ramming  caused  a  barrow 
full  of  earth  to  bulge  up  between  the  holes.  On  the  ground 
thus  prepared  a  mass  of  masonry  was  constructed  and  loaded 
with  lead  as  before,  and  the  settlement  was  as  follows  : 

15  tons  caused  a  settlement  of  1-10  inch. 
29  tons         "  "  2-5  inch. 

These  weights  were  placed  in  April  and  remained  on  till  De- 
cember, when  the  increased  settlement  amounted  to  f  of  an 
inch.  The  load  being  reduced  to  10  tons,  no  further  settlement 
took  place  between  December  and  May."  Other  cases  of  the 
employment  of  sand-piles  are  given  in  the  same  reports  ;  but 
this  is  sufficiently  specific  and  forcible  to  satisfy  any  reasonable 
doubt  as  to  that  employment  in  the  foundation  of  Levees. 
Some  of  the  cases  given  have  been  in  situations  where  the  silt 
and  alluvium  was  over  sixty  feet  in  depth.  Let  the  holes  then 
be  opened  as  they  may,  pack  them  well  with  sand  as  close  to 
each  other  as  the  circumstances  of  the  case  may  demand  ;  and 
the  result  will  be,  in  all  cases,  an  accession  to  the  strength  of 

the  foundation,  and,  therefore,  to  the  stability  of  the  Levee. 

7 


98  PRINCIPLES   AND   PEACTICE  OF 

Brush  and  sand  combined  will  undoubtedly  sustain  the  heaviest 
Levee  under  even  the  most  unfavorable  circumstances  ;  and 
the  most  available  and  cheapest  materials  for  the  purpose 
being  thus  sufficient  for  the  requirements  of  any  case,  it  is  un- 
necessary to  consider  any  other  methods  than  those  based  on 
the  use  of  these  for  accomplishing  that  important  object  in 
Leveeing,  substantial  foundations. 

The  difficulty,  however,  of  meeting  every  particular  of  im- 
proved construction  in  the  Levee,  lies  in  the  sneer  of  the 
purse-holders  in  the  case  at  what  it  calls  "  College"  Leveeing. 
But  the  taxpayer  who  is  enriched  by  the  Levees  of  the  Missis- 
sippi will  make  a  grave  mistake  in  assuming  himself  exempt 
from  the  hard  lessons  that  have  taught  people  placed  under 
like  circumstances  in  other  countries,  the  wisdom  of  their  pres- 
ent practice  in  water-embankments.  In  order  to  urge  on  the 
popular  judgment  of  the  valley  the  importance  of  the  sugges- 
tions made  .above  for  fencing,  grassing,  and  otherwise 
protecting  the  work,  after  its  construction,  for  mucking,  layer- 
ing, brushing,  and  even  piling,  in  the  course  of  its  construction, 
it  may  be  well  to  add  here  a  few  instances  of  the  costliness  and 
care  involved  in  the  case  of  European  and  Asiatic  water-em- 
bankments. Touching  the  dimensions  recommended  above,  it 
may  be  observed  that  Sir.  Cornelius  Vermuyden  gave  the  em- 
bankments of  the  Welland  in  England  for  a  height  of  8  feet,  a 
base  of  70  feet ;  and  that  of  the  Ouse — with  a  crown  of  ten 
feet — for  a  height  of  8  feet,  a  base  of  60  feet.  The  Ouse  at 
Weisbach  has  for  its  embankment  a  height  of  10  feet  carried 
up  on  a  base  of  100  feet.  Sir  John  McNeill,  in  the  drainage  of 
Lough  Swilly  in  Ireland,  gave  his  embankments  a  base  of  from 
5J  to  6  feet  for  every  foot  of  their  height.  On  the  Lower  Da- 
moodah  in  India,  the  "  Bunds,"  as  "  Levees"  are  there  termed, 
have  a  base  for  4  feet  high  of  23  feet.  In  reference  to  the 
inequality  recommended  in  the  case  of  the  dry  and  the  wet 
slopes  of  Levees,  it  may  be  added  that  the  practice  of  this 


EMBANKING  LANDS  FROM  EIVER-FLOODS.  99 

inequality  is  universal.  Sir  John  McNeill — a  name  distin- 
guished highly  in  his  profession — has  given  the  Lough  S willy 
embankments,  already  referred  to,  an  outside  slope  of  from 

3  to  1  to  4  to  1,  while  the  inside  slope  is  but  2  to  1. 

Sir  John  Rennie  reports  the  construction  of  an  embankment 
in  connection  with  the  Commissioners  of  the  Nene  Outfall,  the 
dimensions  of  which  were  5|  to  1  to  seaward,  3  to  1  to  landward, 
the  top  being  4  feet  broad.  Arthur  Young,  in  his  agricultural 
reports,  mentions  several  cases  of  embanking,  one  of  which  he 
says  was  erected  in  1800  :  the  dimensions  were  for  the  sea  slope 

4  to  1,  land  slope  2  to  1,  12  feet  in  height  and  4  feet  broad  on 
top.    The  Dikes  of  Holland — constructed  principally  as  defences 
from  the  sea — are  generally  raised  30  feet  above  the  ordinary 
level  of  the  country.    Banks  have  been  occasionally  made  twelve 
feet  wide  on  top,  and  carried  2  feet  above  the  high-watermark, 
they  were   in   some    positions   turfed    and    strengthened  in 
various  places  with  stakes,  or  piles  and  planking.     Sometimes 
banks  were  formed  by  driving  rows  of  piles  or  stout  stakes 
parallel  to  the  river  at  distances  of  from  2  to  3  feet  apart,  and 
after  uniting  their  heads  by  a  plank,  or  weaving  rods  around 
them,  the  parallel  spaces  between  were  filled  up  with  chalk 
or  some  other  hard  substance.     Banks  made  of  sand,  in  which 
twigs  of  brush-wood  are  placed  horizontally  and  clayed  properly 
with  from  1  to  2  feet  thick  of  clay,  are  found  to  stand  remark- 
ably well.     Coroboratory  of  the  stress  laid  upon  the  selection 
of  clay  for  Levees,  it  may  be  observed  that  in  Holland,  where 
the  system  of  water-embankment  is  carried  out  under  all  the 
experience  of  centuries  of  disaster  and  destruction  of  life  and 
property,  and  where  the  adoption  of  the  best  mode  in  each 
particular  is  a  question  of  national  concern,  sand  in  the  site  of 
the  Levee  is  rejected  when  better  material  cannot  be  obtained 
short  of  a  haul  of  even  Jive  miles.     In  Europe,  no  trouble  or  cost 
is   spared  in  the  construction  of  water-banks  to  make  them 
perfectly  water-tight.     Carrying  up  within  the  work  a  wall  of 


100  PRINCIPLES  AND    PRACTICE  OF 

puddle,  a  practice  which  is  known  by  every  Engineer  to  be 
universal  in  the  construction  of  all  water-tight  embankments, 
does  not  require  for  its  endorsement  an  isolated  instance  like 
even  that  in  the  banks  of  the  S willy-drainage  in  the  practice 
of  Sir  John  McNeill.  The  care  recommended  in  reference  to 
the  foundations  of  Levees  is  borne  out  by  general  usage  in  such 
works — in  England,  in  Ireland,  in  France,  in  Holland,  in  Ger- 
many, in  India.  The  preservative  measures  urged  above  are 
but  modifications  based  on  universal  practice.  In  England  and 
in  France  water-banks  are  regularly  "  turfed  ;"  and  in  weak 
places  protected  with  even  stakes  and  piles.  In  Holland  the 
water-banks  are  protected  on  the  outside  by  a  strong  coating 
or  matting  of  Saggers  and  reeds ;  and  on  the  inside  are  sus- 
tained by  piles  and  planking,  the  slopes  being  coated  thickly 
with  grass.  In  the  Swilly  works,  as  illustrating  the  latest  practice 
and  highest  experience  in  Europe,  it  may  be  remarked  that  the 
land-slopes  of  the  embankments  were  all  covered  with  turf ; 
the  water-slopes  having  been  protected  with  a  facing  of  fascines 
six  feet  thick  at  bottom  and  4  feet  thick  at  top,  these  fascines 
being  laid  in  an  oblique  direction  in  the  slope  and  fastened 
thereto  firmly  by  forks  of  iron.  Reason  then  has  been  first 
appealed  to  herein  urging  the  adoption  of  the  care  recommended 
in  the  construction  and  protection  of  Levees;  and  these  last 
references  to  the  subject,  show  that  the  suggestions  of  reason 
in  the  premises,  are  fully  endorsed  by  the  general  practice. 
But  another  point  for  viewing  the  subject  may  be  illustrated  by 
a  reference  to  the  cost  of  ^Levee-maintenance.  In  Zealand  the 
maintenance  of  their  embankments — 300  miles  in  length— cost 
them  annually  $800,000  !  The  maintenance  of  the  embankments 
and  the  regulation  of  the  water-levels  in  Holland,  cost  the 
enormous  sum  of  $3,000,000  a  year  !  Sea-banks  those  works  in 
both  Zealand  and  Holland  chiefly  are  ;  but,  on  the  other  hand, 
it  must  be  observed  that  in  reference  to  the  cost  of  their  main- 
tenance they  have  been  constructed  with  the  best  material  in 


EMBANKING   LANDS    FEOM   RIVER-FLOODS.  101 

the  best  manner,  and  their  preservation  has  been  guarded  since 
the  time  of  their  construction,  with  all  available  preservatives 
against  decay.  River-embankments,  it  is  true,  the  Levees  of 
the  Mississippi  are  j  but  it  must  be  recollected  that,  until  the 
management  of  one  portion  of  those  works  by  Col.  Alcorn,  very 
little  care  whatever  had  been  taken  in  their  construction,  and 
equally  little  in  their  preservation.  The  maintenance  tax  then 
must  continue  a  heavy  burden  for  some  time  to  come  on  pro- 
perty-holders within  the  Levee  j  and  this  tax  is  subject  to 
reduction  in  only  the  amount  of  care  expended  in  constructing 
new  Levees  and  in  preserving  both  new  and  old.  The  method 
of  construction  and  the  means  of  protection  after  construction 
recommended  above,  are  thus  seen  to  be  means  adapted 
to  reduction  of  taxation  for  Levee  purposes  on  the  parties 
chargeable  with  their  maintenance.  In  this  point  of  view  then 
it  is  hoped  the  popular  judgment  will  hesitate  before  it  under- 
takes to  sneer  away  recommendations  so  influential  for  public 
good  as  mere  "  College  "  nonsense.  These  remarks  are  intended 
not  for  the  intelligence  of  the  valley ;  but  for  the  guidance  of  that 
popular  mind  which  may  stand  at  the  ballot-box,  an  impassable 
obstacle  to  even  such  a  bold  and  talented  reformer  of  the  Levee- 
system  as  the  distinguished  gentleman  to  who  this  volume 
is  inscribed. 


102  PRINCIPLES  AXD   PRACTICE  OF 


CHAPTER    Y. 


HIGH    WATER     MARK. 

THE  municipal  line  is  supposed,  under  the  present  law  in 
Mississippi,  to  make  each  down-stream  County  higher  than  the 
flood  that  may  inundate  the  County  above  it.  Boliver  is, 
therefore,  assumed  to  have  no  concern  in  the  drainage  of  Coa- 
homa.  Engineering,  then,  must  trim  its  practice  to  meet  the 
absurd  system  of  mere  County  jurisdictions.  The  wide  revi- 
sion suggested  hereafter,  for  the  correction  of  flood-levels  in 
Levee-surveys,  cannot  be  carried  out  satisfactorily  at  present ; 
and  hence  does  it  become  necessary  to  offer  a  few  remarks  on 
flood-levels  in  connection  with  the  cramped  working  of  the 
existing  Levee-law.  Simple  as  it  may  appear,  the  establish- 
ment of  the  High  "Water  Mark  along  the  lines  of  Levee,  is  very 
often  a  source  of  difficulty  even  to  the  skillful,  and  of  error  to 
the  unskillful  administrator  of  Levee  Engineering.  *  And 

*  Illustrative  of  the  errors  in  construction  resulting  from  want  of  skill  in  deter- 
mining High  Water  Mark,  the  following  extract  is  made  from  the  Report  of  1856, 
by  the  then  Commissioner  of  Levees,  in  Tunica — Judge  Hardeman: — "The  pro- 
file of  Mr.  Hewson's  survey,  &c.  *  *  *  *  On  being  with  him  during  the  survey, 
and  his  taking  the  field  notes  of  the  same,  it  has  been  clearly  indicated  to  me,  that 
all  the  Levees  heretofore  built  in  the  County,  — except  that  portion  built  and  repaired 
the  past  season — are  from  one  to  two  feet  too  low,  &c.  These  Levees  should  claim 
our  first  attention  and,  if  possible,  be  repaired  the  coming  season."  Judge  Harde- 
man might  have  even  stated  that  the  profile  from  which  he  speaks,  showed  some 
stretches  of  the  embankments  so  much  above  High  Water  Mark  as  5|  feet ;  while  it 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  103 

error,  be  it  recollected,  in  this  particular  is  the  most  dangerous 
that  can  happen  in  all  the  facts  affecting  the  system.  In  the 
first  place,  it  requires  great  caution  in  accepting  testimony, 
generally  more  or  less  hazardous  and  loose,  as  conclusive. 
Checking  the  flood-levels  above  and  below  the  point  of  diffi- 
culty in  such  a  case,  is  the  only  means  of  passing  from  such 
conflicts  of  authority  to  fact.  Nor  in  making  such  a  compari- 
son must  it  be  concluded  that  the  rate  of  descent  of  flood-water 
is  always  that  of  uniformity.  Across  a  bend  it  may  be  very 
rapid ;  whereas,  the  line  of  flow  crossed  by  a  dense  forest, 
thicket,  or  cane-brake,  the  flood-line,  for  a  greater  or  less  dis- 
tance up-stream,  will  be  either  that  of  exceptionally  slow 
descent,  or  of  even  a  dead-level.  But  further  difficulties  apply 
to  the  acceptance  of  local  evidence  as  to  High  Water  Mark. 
In  Levees  of  wide  fore-shore,  it  is  a  great,  sometimes  a  danger- 
ous mistake  to  accept  as  absolute  the  High  Water  Mark  cut  on 
a  tree  on  the  spot,  during  the  flood  of  1844,  or  1850,  by  even 
that  oracle  of  flood-facts,  an  "  Old  Surveyor."  The  "  Old  Sur- 
veyor,'7 doubtless,  may  have  even  made  the  mark  at  the  exact 
height  of  the  flood-water,  then  and  there  ;  but  this  amounts  to 
simply  nothing,  when  it  is  recollected  that  the  flood-water  at 
the  point  in  question  was  the  flood-water  of  an  outflow,  and  that 
the  river-bottom,  while  having  a  fall  of  7  or  8  inches  per  mile 
along  its  axis,  has,  across  that  axis,  a  fall  of  5  or  6  inches  per 
mile.  The  Old  Surveyor,  in  short,  forgot  that,  there  being  a 
fall  in  the  outflow  and  also  in  the  ground  from  the  River-bank 
to  his  flood-mark,  the  damming  back  of  that  outflow  would 
throw  up  the  flood-level  proportionally  higher.  This  consider- 

showed  other  lengths,  so  much  as  eighteen  inches  below  High  Water  Mark.  The 
report  made  to  him  on  the  subject,  holds  in  fact  these  words : — "  The  old  Levee,  for 
27  £  miles,  requires  an  average  additional  height  of  1-55  feet,  to  bring  it  up  to  the 
required  height  of  3  feet  above  High  Water;  in  some  cases,  this  length  of 
Levee  was  found  to  dip  below  the  High  Water-level — each  such  dip  involving,  in 
flood-time,  certain  destruction  to  considerable  lengths  of  the  work  above  and 
below  it." 


104  PRINCIPLES  AND   PRACTICE  OF 

ation  is  highly  necessary  in  ascertaining  the  trite  working  High 
Water  Mark.  The  ready-made  Engineering  of  the  first  Levees — 
if  indeed,  it  be  any  thing  more  intelligent  in  some  places  to- 
day— overlooked  the  fact  that  the  flood-marks  across  the  bot- 
tom follow  the  combined  slope  of  ground  and  outflow  ;  and  in 
consequence  of  this  extraordinary  error,  many  a  mile  of  Levee 
has  been  swept  away,  many  a  dollar,  in  both  scrip  and  cash, 
wasted.  In  practical  illustration  of  the  difficulties  of  fixing  the 
High  Water  Mark — a  duty  for  which  every  man  along  the  Mis- 
sissippi regards  himself  perfectly  competent — it  may  be 
observed  here,  that  the  High  Water  Mark  taken,  on  all  the  local 
tests,  at  a  point  on  the  upper  reach  of  "  Old  River,"  at  Port 
Royal,  in  Coahoma  County,  Mississippi,  was  higher  than  the 
High  Water  Mark  taken  with  like  care,  at  a  point  half  a  mile 
down-stream,  by  so  grave  a  difference  as  4J  feet  !  Indeed,  the 
evidence  available  in  the  case  is  so  loose  and  uncertain  a  guide  ; 
and  an  error  in  that  guidance,  involving  the  destruction  of  the 
Levee,  it  is  highly  important,  in  order  to  proceed  under  all  the 
available  lights  with  safety  and  confidence,  that  the  selected 
levels  of  High  Water  Mark  be  compared  one  with  another,  along 
each  whole  drainage  district ;  and,  finally,  be  revised  by  com- 
parison with  the  selected  levels  corresponding  to  them  on 
the  other  side  of  the  river.  But  this  necessity  supposes  an 
improved  system  of  Levee-law  and  Levee-administration.  For 
the  future,  however,  it  is  highly  important  that  the  public 
attention  be  directed  to  the  wisdom  of  recording,  as  often  as 
possible,  along  the  river,  the  height  of  each  year's  flood.  While 
the  memories  of  parties  living  along  the  bank,  on  both  sides, 
are  fresh  with  marks  of  the  late  disastrous  flood,  a  movement 
just  now  would  be  well  timed  for  the  commencement  of  such  a 
system  of  record  from  end  to  end  of  the  inundated  shores. 
Well-ascertained  evidence  of  this  sort  may  be  fixed  at  once,  by 
the  leveller;  and  after  comparison  and  selection  of  all  the  facts, 
he  may  transfer  the  revised  flood-heights  to  a  series  of 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  105 

Bench  Marks,  sunk  for  the  purpose,  at  intervals,  inside  the 
Levee.  These  Bench  Marks  should  be  driven  down,  firmly, 
three  or  four  feet  into  the  ground,  so  as  to  guard  against  their 
being  broken  or  sunk  ;  and  when  their  levels  may  have  been 
duly  ascertained,  that  of  each  in  reference  to  its  flood-level 
should  be  marked  in  red  chalk  or  paint  on  one  side,  the  num- 
ber of  the  Bench  Mark  being  marked,  likewise,  (in  order  to 
identify  it)  on  the  other  side.  This  use  of  Bench  Mark-stakes 
is  -universal  in  the  Engineering  practice  on  the  "Dikes"  of 
Holland  ;  and  like  most  of  the  usages  established  for  the  con- 
duct and  maintenance  of  those  works,  is  highly  applicable  in 
the  case  of  the  Mississippi  embankments. 


106  PRINCIPLES  AND   PRACTICE    OF 


CHAPTER   VI. 


LOCATION. 

The  location  of  a  line  of  Levee  is  a  consideration  involving 
permanence — involving  economy  of  construction  and  economy 
of  maintenance.  Large  sums  of  money  have  been  expended  in 
Levees  which,  in  several  instances,  have  within  twelve  months  of 
tJicir  construction  fallen  into  the  river.  The  cause  of  this  has 
been  ignorance  or  carelessness  in  determining  the  location. 
Private  interest,  however,  is  very  often  a  disturbing  influence 
in  forcing  the  location  of  Levees  from  the  line  of  safety  and 
economy.  A  Planter  has  frequently  been  known  to  be  so  short- 
sighted as  to  have  urged,  and  in  fact  obtained,  the  location  of  a 
Levee  around  three  sides  of  even  a  "  turnip  patch"  rather  than 
consent  to  the  necessity — to  himself  as  well  as  to  the  general 
public—of  locating  that  Levee  in  continuance  of  its  proper  align- 
ment directly  across  that "  turnip  patch."  *  The  increased  cost 

*  In  the  address  explanatory  of  the  causes  of  Levee  failure  during  the  late  flood 
of  the  Mississippi,  the  Coahoma  Commissioner,  while  putting  the  scientific  conside- 
rations of  the  case  in  good  popular  terms,  caps  those  considerations  by  reference  to 
late  practical  experience  ;  on  pages  17  and  18  he  says :  "  Motion,  whether  of  solids  or 
fluids,  naturally  follows  straight  lines ;  and  all  deviations  from  that  law  are  accom- 
plished by  an  expenditure  of  impulse  on  the  object  occasioning  that  deviation.  A 
sudden  turn  in  a  stream  concentrates  the  whole  energy  of  the  fluid-motion  on  the 
one  point,  occasioning  that  sudden  turn,  hence  the  danger  of  all  sudden  turns  in  the 
Levee.  In  the  original  locations  of  the  Levee  all  these  laws  of  motion  were  violated ; 
no  regard  whatever  was  paid  to  the  alignment;  it  was  made  to  wind  itself  around 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  107 

of  constructing  the  embankment  to  meet  this  gentleman's  nar- 
row-minded views,  as  compared  with  the  cost  of  constructing 
the  embankment  on  its  proper  alignment,  has  very  often  been 
ten  times  greater  than  the  whole  value  of  the  additional  piece 
of  ground  he  had,  by  forcing  the  Levee  out  of  its  course,  suc- 
ceeded in  enclosing.  This,  however,  is  not  the  only  injustice 
done  under  such  circumstances  to  the  body  of  the  tax-payers  ; 
for  in  making  the  Levee  on  the  zig-zag  necessary  for  the  gentle- 
man's purposes,  that  course  is  subject  to  the  additional  injus- 
tice of  either  reconstructing  the  work  on  the  proper  ground 
when  the  zig-zag  may  have  fallen  into  the  river,  or  of  flooding 
the  whole  back-country  when  the  shock  of  the  high-water  cur- 
rent striking  against  it  directly,  bursts  its  way  in  a  "  crevasse" 
through  that  zig-zag's  up-stream  juttings.  The  location  of 
Levees,  then,  it  may  be  seen  from  these  remarks,  should  not  be 
a  mere  matter  of  random  ;  but  should  be  determined  thought- 
fully with  a  view,  in  the  first  place,  to  the  progress  of  the 
river  whether  in  "  caving"  or  "  making,"  and  with  a  view  in 
the  next  place  to  the  obviation  of  current-shocks. 

In  locating  a  Levee,  the  first  duty  is  the  mapping  out  care- 
fully of  the  bank ;  and,  as  far  as  may  be  done,  by  a  careful 
sketching  of  the  current-set,  the  "  caving,"  and  the  "making." 
In  the  case  of  cavirigs  and  makings,  every  information  as  to 
their  commencement,  their  rate  of  progress  inwards,  and  their 
advance  doww-strearn,  should  be  obtained  carefully  from  local 
information  and  recorded  at  the  proper  points  upon  the  map. 
The  cavings  and  the  makings  of  the  bank  pass  down-stream  in 
a  series  of  waves,  period  after  period  ;  and,  therefore,  by  ascer- 
taining the  rate  of  descent,  the  rate  of  penetration  of  a 

every  cow-pen  or  horse-lot,  presenting  obtuse  angles  in  the  work  at  many  critical 
points ;  and  that,  too,  without  any  increased  strength  of  embankment  at  those 
points.  At  many  such  places  the  Levee  during  the  late  rise  gave  way,  for  the  reason,  as 
assigned,  it  was  without  strength  to  resist  the  current-shock."  The  most  zealous  and 
best  informed  friend  of  the  Levee-system  thus  urges!  and  endorses  the  importance  of 
proper  attention  to  the  question  of  alignment. 


108  PRINCIPLES  AND   PRACTICE   OF 

"  cave,"  or  extension  of  a  "  make"  at  the  point  of  its  operation, 
the  location  of  the  Levee  opposite  that  point  may  be  made 
with  a  full  knowledge  of  the  conditions  of  its  permanence. 
Levees  built  one  year  under  such,  evidently,  necessary  precau- 
tions, will  not  be  swept  into  the  river  within  either  a  few 
years  or  a  few  months  after  their  construction.  In  order  to 
illustrate  this  important  point  more  fully,  the  method  of  mak- 
ing, and  indeed  of  applying,  the  notes  of  "  caving"  and  of 
"  making"  as  recommended  here,  may  be  impressed  upon  the 
understanding  of  young  Engineers  more  readily  by  a  speciality. 
With  this  view  then  is  given  the  following  instances.  The 
Chief  Engineer  of  the  Mississippi,  Ouachita  and  Red  River 
Railroad,  having  located  the  Eastern  Terminus  of  that  road  at 
a  point  which  failed  to  satisfy  some  of  the  stockholders,  Mr. 
M.  Butt  Hewson,  then  directing  the  affairs  of  the  Arkansas 
Midland  Railroad,  was  engaged  to  report  upon  the  question. 
The  general  grounds  on  which  the  original  location  had  been 
based  having  been  taken  up  by  that  gentleman  as  the  heads  of 
his  inquiry,  one  of  those  so  made  the  subject  of  his  investiga- 
tion was  the  question  of  an  anticipated  change  of  course  in  the 
river  by  a  "  Cut-off,"  opposite  Games'  Landing.  Mr.  Hewson's 
report  under  this  head  presents  the  following  illustrative 
remarks  applicable  to  the  considerations  referred  to  here  as 
guiding  Levee-locations. 

"  A  long  professional  experience  in  the  improvement  of 
rivers,  a  somewhat  intimate  acquaintance  with  the  laws  of 
fluid-motion,  and  a  few  years  observation  as  a  resident  on  its 
banks,  of  the  habits  of  the  Mississippi,  fail  to  place  my  answer 
to  your  fourth  question  within  the  limits  of  exact  induction. 
It  is  much  safer  to  speculate  than  to  demonstrate  on  the  subject 
of  changes  of  the  Mississippi  River.  I  shall,  however,  furnish 
you  with  the  facts  bearing  on  your  question ;  and  thereby 
enable  you  to  judge  for  yourself  as  to  the  logical  justice  of  my 
inferences. 


EMBANKING  LANDS  FROM  EIVER-FLOODS.  109 

"  One  general  law  of  the  Mississippi  River — subject  like  all 
general  laws  to  special  exceptions — is  very  plain,  viz :  the 
progress  of  its  cavings,  like  that  of  its  currents,  is  down-stream. 
In  that  portion  of  the  riverunder  consideration,  the  set  of  the  cur- 
rent from  the  Arkansas  side  struck  the  Eastern  bank,  some  time 
ago,  opposite  the  residence  of  Col.  Martin  ;  whereas,  now,  the 
most  Northerly  thread  of  that  current  does  not  strike  the  same 
bank  for  several  hundred  yards  lower  down.  So  much  for  the 
general  fact  of  the  progression  of  the  cause  of  active  caving.  I 
will  now  call  your  attention  to  the  present  stage  of  this  pro- 
gression in  the  reach  of  river  under  consideration.  Eleven 
hundred  yards  below  Col.  Martin's  house,  the  present  caving 
commences  ;  the  Southern  limits  of  this  caving  is  not  reached 
for  a  further  distance  of  eight  thousand  one  hundred  yards 
still  lower.  The  centre  of  this  existing  impact  on  the  bank 
may,  therefore,  be  deduced  as  midway  between  those  limits  of 
present  caving — that  is  to  say,  4000  yards  below  the  Northern 
limit  of  that  caving.  The  force  of  a  current,  always  a  mini- 
mum at  its  outer  limits,  reaches  its  maximum  in  the  middle  of 
those  limits.  Now,  the  '  Cut-off'  suggested,  abuts  on  the  bank 
at  3700  yards  below  the  Northern  edge  of  present  caving  ; 
and,  therefore,  the  centre  of  impact,  the  point  of  greatest 
effect,  having  already,  in  its  steady  progress  down-stream, 
passed  below  the  site  of  the  assumed  '  Cut-off'  for  a  distance 
of  300  yards,  we  may  reasonably  conclude  that,  so  far  as  the 
supposition  of  this  *  Cut-off'  is  concerned,  the  period  of  maxi- 
mum expectation — of  greatest  likelihood — is  irrevocably  passed. 
The  beam  that  sustains  the  pressure  of  ten  tons  must  be  sup- 
posed perfectly  safe  from  fracture  under  a  like  pressure  of 
nine  tons.  In  consideration  of  these  general  facts  of  the  case, 
the  inference  is  clearly  opposed  to  the  supposition  of  this 
*  Cut-off.'  In  order  to  examine  the  same  question  from 
another  point  of  view,  I  will  present  an  analysis  of  the  evidence 
as  to  amount  and  rate  of  caving,  furnished  by  gentlemen  living 


110  PRINCIPLES  AXD    PRACTICE  OF 

on  the  ground,  at  the  several  points  along  the  line  of  this  pro- 
gressing impact.  Dr.  Offutt  states,  that  opposite  his  house  (a 
point  above  Mr.  Daniel's  house)  the  bank  has  caved  400  yards 
in  20  years  ;  but  at  a  less  rapid  rate  for  the  last  ten  of  these, 
than  for  the  previous  ten  ;  and  for  the  last  four  of  these  latter 
ten,  still  more  slowly.  Mr.  Wallace  affirms  that  the  bank  at 
the  same  point,  has  caved  100  yards  for  the  last  7  years  ;  and 
as  compared  with  the  gross  average  of  these  seven,  '  very 
little7  for  the  last  2  years.  At  this  place  the  bank  has 
caved  : 

Within  the  last  20  years,  at  the  rate  per  year  of  20  yards : 
Within  the  last  10  years,  at  a  rate  per  year  of  less  than  20  yards : 
Within  the  last  7  years,  at  the  rate  per  year  of  14|  yards : 
Within  the  last  2  years,  at  a  rate  per  year  of  very  little. 

"  Here,  then,  is  a  constant  diminution  of  the  effect — a  dimi- 
nution in  direct  accordance  with  the  passing  away  of  the 
operating  cause.  Opposite  Mr.  Daniel's,  (a  point  above  the 
suggested  '  Cut-off)  the  bank  has.  on  the  authority  of  Dr.  Offutt, 
caved,  in  twenty  years,  five  hundred  yards  ;  the  greater  part 
within  the  last  ten  years,  while  the  caving  for  the  last  year  has 
been  at  a  lower  rate.  Mr.  Wallace's  testimony  as  to  this  point, 
places  the  cavings  at  two  hundred  yards  within  the  last  seven 
years  ;  but  for  the  last  two  years,  very  little.  These  eviden- 
ces stand  thus  :l 

Within  the  last  20  years,  at  the  rate  per  year  of  25  yards : 
Within  the  last  10  years,  over  25  yards : 
Within  the  last  7  years,  28j  yards : 
Within  the  last  2  years,  much  less. 

"  In  this  increase  of  effect,  up  to  a  certain  time,  and  diminu- 
tion of  effect  since  that  time,  we  obtain  further  evidence  of  the 
Southern  movement  of  the  centre  of  impact.  Twenty  years 
ago,  it  had  not  reached  so  low  down  as  Daniel's  ;  and,  conse- 
quently, did  not  then  produce,  at  that  point,  its  highest  effect ; 


EMBANKING  LANDS  FROM   RIVER-FLOODS.  Ill 

but  as  it  advanced,  its  progress  is  traced  in  the  higher  effect 
of  the  last  ten  years  ;  in  the  still  higher  effect  of  the  last  seven 
years  ;  and,  as  it  passed  further  South,  its  continued  progress 
in  the  diminished  effect  of  the  last  two  years.  The  point  upon 
which  the  suggested  *  Cut-off7  abuts  upon  the  bank  has,  accord- 
ing to  Mr.  "Wallace,  caved  one  hundred  yards  within  the  last 
seven  years  ;  but  for  the  last  three  years  of  these  seven,  at  a 
lower  rate  :  whereas,  on  the  authority  of  the  same  gentleman, 
the  bank,  opposite  Mr.  Wilkerson7s,  (a  point  below  the  suggested 
4  Cut-off7)  having  caved  three  hundred  yards  within  the  last 
20  years,  has  maintained  a  higher  rate  of  caving  for  the  last 
ten.  This  point  opposite  Wilkerson7s,  coincides  with  the  pre- 
sent centre  of  impact,  as  inducted  above,  from  the  existing 
limits  of  effect  upon  the  bank ;  and  hence  we  may  infer  with 
logical  propriety,  that  the  energy  (as  evinced  in  the  effects) 
has  been  increasing  at  that  point  for  years  ;  and  being,  now, 
at  its  highest,  must  from  this,  forward,  steadily  diminish,  until  it 
shall  have,  ultimately,  passed  altogether  away.  Below  Wilker- 
son7s,  the  testimony  of  Messrs.  Offutt,  Wallace,  and  Harris, 
shows  an  increasing  energy  in  the  increasing  effect ;  and,  there- 
fore, as  far  as  the  irregularity  of  the  outline,  and  the  resistance 
of  the  soils  will  admit  of  a  strictly  exact  result  in  such  a  case, 
demonstrating  the  present  centre  of  effect  to  be  below  the  *  Cut- 
off/ leads  irresistibly  to  the  inference  that  the  time  to  speak 
of  the  suggested  '  Cut-off7  as  within  the  limits  of  probability, 
has  passed  away.  What  the  maximum  impact  failed  to  accom- 
plish cannot  be  expected  from  a  minor  impact  •  nor  is  there  any 
irregularity  in  the  general  outline  of  the  bank  to  direct  a 
special  current  against  the  debouch  of  the  suggested  '  Cut-off;7 
that  outline,  being  in  general  a  regular  curve,  may  be  held  to 
receive,  in  the  consequent  uniformity  of  its  resistance,  an  effect 
equally  distributed.  The  rate  of  caving  at  the  supposed  '  Cut- 
off/ proves  that  the  bank  at  that  point  is  not  inferior  in  cohe- 
sive strength,  to  that  at  any  other  point  included  in  the 


112  PRINCIPLES   AXD   PRACTICE  OF 

information  obtained  in  the  case.  Besides,  the  result  suggested 
must  now,  if  it  come  at  all,  come  from  one  side  ; .  for  the  East- 
ern debouch  of  the  '  Cut-off'  has  a  making  bank.  If,  then,  the 
*  Cut-off'  is  to  result  from  its  present  rate  of  caving,  it  will  not, 
unless  under  some  new  and  special  combination  of  causes,  occur 
for  upwards  of  a  century  and  a  half.  This  supposes  the  centre 
of  effect  constant  in  its  point  of  application  ;  but  with  the  cen- 
tre traveling  steadily  to  the  Southward,  the  accomplishment  of 
such  a  result  must  be  deferred  indefinitely.  To  sum  up  these 
remarks  on  the  suggested  '  Cut-off :'  if  the  facts  of  the  case  do 
not  positively  establish  that  the  '  Cut-off'  will  not  be  made, 
they  go  far  to  prove  that  such  a  supposition  is  entirely 
improbable." 

The  Keport  still  further  sketches  out  the  method  of  reason- 
ing, from  the  observed  facts  of  "  Making,"  and  "  Caving,"  in 
the  following  consideration  of  the  question  of  increased  shoal- 
ing at  Games'  Landing  : — 

"  To  meet  your  fourth  question  broadly,  I  must  consider 
what  other  changes,  as  the  supposition  of  the  Cut-off  must 
clearly  be  rejected,  is  most  likely  to  take  place  in  the  Eiver 
between  Ferguson's  Point  and  Games'  Landing.  The  align- 
ment of  the  River  above  the  Railroad  Terminus  shows,  as 
detailed  above,  a  change  of  course,  in  a  distance  of  three  and 
a  half-miles,  of  ninety  degrees  :  in  other  words,  the  Mississippi 
River,  curving  from  a  point  about  three-quarters  of  a  mile 
above  the  Railroad  Terminus  until  it  fronts  the  house  of  Mr. 
W.  C.  Campbell-^-a  distance  of  three  and  a  half  miles — turns 
fully  one-quarter  round.  To  divert  the  whole  volume  of  the 
Mississippi  River  so  far  from  its  direct  course,  implies  the  ex- 
penditure by  the  River  of  an  immense  energy  on  the  resist- 
ance causing  this  divergence  ;  and  hence  may  we  understand, 
in  a  general  way,  the  amount  of  the  force  employed  in  opera- 
ting on  the  bank  between  Mr.  Campbell's  plantation  and  the 
site  of  the  Railroad  Terminus.  The  caving  consequent  on  the 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  113 

force  so  exerted  against  the  bank  between  those  points,  stands 
at  present  in  its  progress  to  the  southward,  as  follows  :  It 
begins  at  a  point  500  yards  below  Mr.  Campbell's  ;  and  extend- 
ing down  the  River-bank, to  the  head  of  Island  No.  80,  a  point 
1200  yards  below  the  Railroad  depot,  the  centre  of  impact  (the 
point  of  greatest  effect)  being  at  the  present  time  situated, 
therefore,  upwards  of  2700  yards  higher  up-stream  than  the 
Railroad  Terminus.  The  rate  of  effect  at  points  along  this 
bank  I  am  unable  to  say  ;  but  the  maximum  effect  having  yet 
to  operate  over  a  space  of  2700  yards  before  it  shall  have 
reached  the  Terminus,  has  yet,  in  obedience  to  an  infallible  law 
of  the  River,  to  come  sweeping  down  with  all  its  powers  of 
change  and  destruction  on  what  remains  of  Ferguson's  Point. 
In  the  march  down-stream  of  the  axis  of  current  lies  the  cause 
of  any  such  change  of  channel  as  may  be  looked  for  between 
the  Railroad  Terminus  and  Games'  Landing.  When  the  cur- 
rent of  the  River  first  swept  the  Northern  bank  of  Ferguson's 
Point,  the  Southern  bank  of  that  point  lay  at  the  head  of  a  line 
of  slack-water.  Island  80  resulted  from  this  ;  for  the  matter 
that  passes  off  in  suspension  under  the  impulse  of  a  current  of 
4  or  5  miles  an  hour,  will  be  precipitated  in  currents  of  one 
or  two  miles  an  hour.  Now,  however,  Ferguson's  Point  has 
been  to  a  considerable  extent  carried  away,  within  the  last  six 
years,  to  an  extent,  according  to  Col.  B.  Gaines  and  Mr. 
Reinhart,  of  eighty  yards  ;  and  as  a  consequence,  the  Island 
formed  under  the  shelter  of  that  Point  begins  now  to  receive 
the  shock  of  the  river  current."  Observations  and  applica- 
tions of  the  above  description  being  employed  as  a  guide  in 
the  case  of  the  location  of  Levees,  the  determination  of 
those  locations  may  be  made  with  a  proper  regard  to  the  most 
important  considerations  affecting  their  permanence.  All 
points  of  the  bank  being  thus  examined  under  the  light  of  the 
circumstances  affecting  their  permanence,  the  limits  of  per- 
manence inferred  therefrom,  must  be  noted  at  intervals  on  the 


114  PRINCIPLES  AND  PRACTICE  OF 

plan  ;  and  the  alignment  of  the  Levee  being  made  to  conform  to 
the  considerations  proper  to  itself,  the  location  must  be  laid 
down  on  the  plan  within  the  restrictions  of  these  limits  of 
permanence.  The  laws  governing  the  alignment  of  water- 
embankments,  like  those  governing  the  alignment  of  Railroad 
tracks,  point  in  the  first  instance  to  straight  lines.  The  course 
of  motion,  whether  of  solids  or  fluids,  is  naturally  rectilineal. 
As  has  been  observed  in  the  latter  of  the  two  foregoing  ex- 
tracts from  the  report  of  Mr.  Hewson,  the  diversion  of  motion 
from  its  original  line  to  any  other  line,  involves  the  expendi- 
ture of  more  or  less  mechanical  effect.  In  diverting  a  surface 
layer  of  the  Mississippi  flood-water — that  mass  moving  at  the 
rate  of  some  6  miles  an  hour — from  one  course  to  another,  it 
can  be  readily  understood  that  the  expenditure  of  mechanical 
effect  is  very  great.  In  order,  then,  to  discharge  this  unavoid- 
able force  with  the  least  possible  danger  to  the  Levee,  it  should 
(so  that  it  be  distributed  equally  over  a  large  space)  be  dis- 
charged invariably  over  a  curve.  These  few  simple  principles 
point  out  clearly  the  rules  governing  Levee  alignment — 
straight  lines  where  such  are  practicable,  and  regular  curves 
where  they  are  not.  Laying  down  this  curvilinear  rectilinear 
alignment  in  a  manner  as  far  as  possible  to  accord  with  the 
general  lines  of  the  river-currents,  the  Levee  will  be  exposed 
at  all  its  points  to  the  least  possible  shocks  and  washes.  The 
limits  of  permanence  laid  down  on  the  plan  according  to  the 
considerations  premised  above,  the  lines  of  current  controling 
the  general  direction  of  the  alignment,  that  alignment — making 
all  its  changes  of  direction  over  regular  curves — may  be  laid 
down  finally  on  the  plan  with  the  fullest  faith  in  it  as  the  loca- 
tion of  greatest  safety  and  greatest  economy.  Often,  however, 
it  will  occur  in  reasoning  on  the  considerations  guiding  in  lay- 
ing down  the  Levee-route  on  the  plan,  that  two  or  more  routes 
may  appear  to  possess  equal  merits.  Laying  down  all  these 
routes  on  the  map,  each  must  be  made  a  subject  of  instrumen- 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  115 

tation  and  estimation  ;  and  always  taking  into  consideration 
that  the  closer  the  alignment  adheres  to  the  limits  of  perma- 
nence the  greater  the  amount  of  good  to  the  public,  the  relative 
cost  of  the  respective  routes  determining,  finally,  as  to  the  one 
for  adoption.  So  much  then  for  the  general  considerations 
affecting  location.  Special  considerations  in  reference  to 
stretches  of  considerably  heavy  embankment,  may  apply — 
such,  for  instance,  as  ridges  furnishing,  within  the  limits  of 
permanence,  an  economical  location  for  the  Leveeing  of  a  neck 
of  swamp.  These  must  in  all  such  cases  be  examined  carefully 
— first  by  the  reconnoisance  of  a  professional  eye,  and  next,  if 
found  necessary,  by  instrumentation  and  estimation.  So  much 
then  for  the  considerations  applicable  to  location  under  the 
cramped  action  of  the  Mississippi  Levee-laws. 


116  PRINCIPLES  AND   PRACTICE  OP 


CHAPTER    VII. 


SURVEYS . 

HIGH  Water  Mark,  it  has  been  shown,  cannot  be  obtained  so 
readily  as  is  supposed  by  the  populace.  On  the  contrary,  the 
correct  determination  of  the  flood-line  for  fixing  the  height  of 
a  Levee,  is  a  duty  that  involves,  not  only  sound  judgment  and 
patient  investigation  ;  but  also  careful  and  extensive  instru- 
mentation. The  location  of  a  Levee,  it  has  also  been  pointed 
out,  is  something  more  than  a  matter  of  off-hand  expediency. 
This  duty  of  the  Levee-system  is  at  present — like  the  determi- 
nation of  the  flood-line — assumed  popularly  to  be  fully  within 
the  knowledge  and  capacity  of  every  man  living  on  the  banks 
of  the  river.  The  considerations  affecting  the  discharge  of 
such  a  task  have,  however,  been  shown  already  to  be  too  in- 
tricate, too  extensive,  too  delicate,  to  be  grouped  and  combined 
into  correct  results  by  even  men  of  fair  standing  amongst  the 
members  of  the  profession  as  Field  Engineers.  Location,  with 
the  commonest  pretensions  to  care  and  science,  requires,  as  has 
been  indicated  in  the  remarks  on  that  head,  as  a  first  necessity, 
a  full  careful  survey,  an  exact  and  special  map.  The  first  duty 
then  of  an  improved  system  of  Leveeing  should  be  the  prepar- 
ation of  maps  and  profiles — the  surveys  for  those  maps  and 
profiles  to  be  extended  from  end  to  end  of  those  sections  of 
country  referred  to  hereafter  as  Drainage  Districts.  These 
surveys  can  be  directed  only  by  a  mind  quick  in  observation 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  117 

and  ingenious  in  inference — this  quickness  and  ingenuity  guided 
by  a  familiarity  with  fluid-motion  and  river  phenomena.  They 
should  show  by  actual  offset-chaining  the  line  of  bank  ;  and  by 
careful  sketching,  all  "  makes,"  "  bars,"  and  currents.  These 
instrumentations  should  bring  out  all  the  facts  of  cavings,  so 
as  to  furnish  to  the  mapper  the  penetration,  progress,  and 
stage  of  each  cave.  All  facts  of  possible  or  probable  influence 
on  the  objects  of  the  survey — such  for  instance  as  the  facts  of 
Moon  Lake  in  Mississippi,  of  Old  Town  Lake  in  Arkansas,  of 
Bayou  Atchafalya  in  Louisiana,  their  position,  form,  level, 
flow,  &c.  &c — ought  to  be  carefully  ascertained  and  connected 
with  the  great  body  of  the  facts  of  the  District  survey.  Every 
foot  of  survey,  whether  of  experimental  lines  along  ridges, 
across  swamps,  or  any  where  else,  within  a  Drainage  District, 
should  be  laid  down  regularly  when  completed  and  connected 
with  the  general  survey  on  the  plans  and  profiles  of  that  Dis- 
trict. These  plans  should  consist  of  two  sets  ;  one  set  on  a 
scale  as  large  as  practicable  for  a  map  of  convenient  size, 
showing  the  ground  along  the  whole  front  of  its  whole  District. 
Divided  into  squares  by  light  lines  across  its  face,  this  map 
should  be  made  an  index  map  by  numbers  set  on  each  square 
so  shown,  to  the  several  sheets  of  the  second  set  of  maps — a 
set  made  to  a  sufficiently  large  scale  to  embody  all  the  minutiae 
necessary  for  practical  purposes.  These  enlarged  working- 
plans,  amongst  the  other  particulars  referred  to  as  guides  in 
location,  should  show  the  site  and  title  of  all  survey-stations, 
the  site  and  number  of  all  Bench  Marks,  the  elevations  of  the 
Bench  Marks  recorded  duly  by  transfer  from  the  District  pro- 
file. The  first  exact  and  minute  survey  of  a  Drainage  District 
effected  by  a  special  staff,  the  constant  staff  required  for  the 
Engineering  direction  of  the  District-works,  should  spend  all  the 
spare  time  from  construction-duties,  in  keeping  up,  by  survey, 
connected  records,  on  the  working  plans,  of  all  changes  of  "  bars," 
increases  of  "  makes,"  shiftingsof  currents,  penetrations  and  pro- 


118  PRINCIPLES  AND  PRACTICE  OP 

gressions  of  "  caves."  These  facts  ascertained  and  laid  down 
on  the  plans,  year  after  year,  the  continuity  of  the  records  on 
the  whole  river  will,  after  a  time,  enable  a  Levee-administration 
to  reduce  to  something  like  scientific  exactness,  every  consid- 
eration affecting  the  perfect  practical  efficiency  of  their  most 
important  duties. 

The  maps  described  here  have  been  deduced  as  necessities 
of  location  from  the  circumstances  affecting  it  on  but  one  side 
of  the  river.  But  it  has  already  been  shadowed  out  in  the 
remark  on  that  subject,  that  the  location  of  a  work  on  either 
side  cannot  be  made  with  complete  care  without  the  exact  com- 
parison with  the  location  on  the  side  opposite.  The  practical 
difficulties  referred  to,  under  the  head  of  High  Water  Mark, 
also  suggest  the  comparison  of  levels  on  one  side  of  the  river, 
with  levels  on  the  other  side.  But  the  necessity  arising  from 
these  considerations  is  indicated  still  more  forcibly  from 
another  point  of  view.  The  remarks  offered  on  location  show 
the  necessity  of  avoiding  all  causes  of  excessive  pressures,  or 
shocks  upon  river-embankments.  The  currents  treated  with 
disregard,  and  the  lines  of  least  resistance  duly  observed,  in 
location  of  a  Levee,  the  conditions  of  location  in  reference  to 
yhocks  are  fully  met,  so  far  as  the  considerations  affecting  them 
on  that  particular  side  of  the  river.  But  let  it  be  assumed  that 
the  Levees  up-stream  have,  on  both  sides  of  the  river,  a  consid- 
erable breadth  of  fore-shore  ;  while  at  the  point  of  this  locally 
judicious  location,  the  Levee  on  both  sides  happen  to  have  for 
their  fore-shore,  each  but  a  narrow  strip.  The  width  from 
Levee  to  Levee,  across  the  river,  may  thus  happen,  up-stream, 
to  be  large,  while  below — at  the  point  of  the  locally  good  loca- 
tion— the  width  across  the  river  from  Levee  to  Levee  may 
happen  to  be  comparatively  narrow.  This  sudden  contraction 
of  the  flood-flow  will  throw  an  increased  shock  of  current  on 
the  Levees  at  the  point  of  that  contraction  j  and  thus  does 
the  location  of  a  Levee  on  one  side,  without  due  regard  to  that 


EMBANKING  LANDS  FROM  EIVER-FLOODS.  119 

of  the  Levee  on  the  other  side,  involve  some  of  those  avoidable 
contingencies  of  breaching  the  embankments  which  judicious 
location  undertakes  to  guard  against.  Proper  location,  then, 
notwithstanding  conformity  with  all  considerations  of  "  cave,'; 
current,  and  alignment,  on  one  side  of  the  river,  cannot  be  made 
without  comparing  the  location  based  on  all  these,  with  the 
location  on  the  other  side.  The  narrowest  width  of  the  river- 
flow,  in  the  natural  state,  is  said,  in  the  late  able  pamphlet  of 
Col.  Alcorn,  to  be  opposite  Randolph,  in  Tennessee.  A  bluff 
at  one  side  and  a  high  bank  on  the  other  side,  it  appears  that 
at  that  place  the  floods  of  the  Mississippi  pass  off,  without  any 
particular  increase  of  current,  or  wear  of  the  bank,  within  a 
width  of  2,000  yards.  A  proper  survey  of  the  river  might,  pro- 
bably throw  further  and  more  correct  light  on  this  particular 
fact ;  but  whether  Randolph  be,  or  be  not  the  site,  and, 
whether  2,000  yards  be,  or  be  not  the  width,  of  the  narrowest 
natural  channel  of  flood-water,  some  site  and  some  width 
answering  those  conditions  ought  to  be  ascertained  for  fixing  the 
ruling  width  of  water-way  between  the  lines  of  river-embank- 
ment. This  ruling  width  determined  in  reference  to  the 
width,  section,  and  current  of  several  "narrows"  in  the  flood- 
flow,  the  proper  location  of  Levees  on  either  side  of  the  river, 
requiring  that  the  flood-width  be  never  lower  than  the  stand- 
ard, such  a  location  on  one  side  can  be  made  only  pari-passu  with 
the  corresponding  location  on  the  other  side.  An  inter-littoral 
survey  is  seen  thus  to  be  a  necessity  of  economic  and  perma- 
nent location.  This  survey  connecting  District  surveys  across 
the  river,  does  not  require  absolutely  to  be  one  of  detail.  In- 
termediate Islands  should  certainly  be  embraced  in  it ;  but  in 
consideration  of  the  cost  of  such  an  extension  of  labor,  it  is, 
perhaps,  better  (for  some  time  at  least)  to  omit  soundings.  A 
skeleton  Trigonometrical  survey,  then,  connecting  stations  in 
local  surveys  on  both  shores,  and  on  intervening  islands,  is  all 
that  is  absolutely  necessary  in  addition  to  the  surveys  already 


120  PRINCIPLES  AND  PRACTICE  OP 

described  for  completing  the  enquiries  and  records  necessary 
to  a  perfectly  correct  and  economic  system  of  Levee-adminis- 
tration. The  triangulation  necessary  for  this  survey,  should 
be  carried  out  with  a  view  to  fixing  each  station  under  the 
endorsement  of  one  or  more  checks  j  but  due  regard  to  be 
paid,  in  all  cases,  to  the  regularity  of  the  shape  of  the  triangles, 
and  to  the  including  in  each  station-book  on  the  field,  of  each 
of  the  stations  that  may  be  possibly  combined  in  any  one 
triangle.  The  correction  of  bases,  the  adjustment,  in  estima- 
tion, of  spherical  excess,  &c.,  are  details  that,  in  addition  to  all 
the  care  suggested  for  the  field,  are  highly  necessary  in  carry- 
ing a  base  line  of  some  2000  or  3000  yards,  with  all  the  correc- 
tions of  even  several  intermediate  checks,  through  a  series  of 
some  eight  or  ten  hundred  triangles.  The  triangulation, 
however,  "  poled  out,"  the  angles  taken,  the  base  measured, 
and  the  calculations  made,  the  District-surveys  may  be  carried 
out  in  detail  as  described,  connecting  regularly  with  the 
stations  of  the  triangulation.  The  diagram  of  the  trigonomet- 
rical points  having  been  laid  down,  the  filling  in  of  this 
diagram,  on  each  side,  with  the  details  of  each  local  survey, 
will  not  only  guarantee  an  accuracy  otherwise  unobtainable  in  that 
local  survey,  but  will  also  present  a  perfect  connection  of  the 
facts  on  both  sides  of  the  river.  This  connecting  survey  will, 
in  the  first  place,  by  doubling  the  data,  lead  to  reliable  infer- 
ences in  all  cases  as  to  the  height  of  High  Water  Mark — will, 
by  embracing  in  exact  detail  the  facts  of  all  the  "  narrows," 
limiting  the  width  of  flood-flow,  lead  to  correct  deductions  as 
to  the  "  ruling"  width  proper  in  the  case  of  opposite  Levees  ; 
and  by  representing  the  relative  position  of  Levee-alignment 
on  each  side  of  the  stream,  point  to  those  modifications  or 
changes  of  site  that  may  be  necessary  for  conformity  with  the 
conditions  of  efficiency  and  permanence. 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  121 


CHAPTER   VIII. 


The  subjects  of  flood-line,  location  and  survey  involve  neces- 
sities at  evident  conflict  with  the  present  system  of  Levee- 
legislation.  In  Arkansas  and  in  Louisiana  the  administration 
of  the  drainage-interests  are  in  the  charge  of  the  State  ;  in  Mis- 
sissippi, in  Tennessee,  and  in  Missouri,  the  charge  of  those 
interests  is  parcelled  out  among  the  Biver-counties.  In  all  these 

*  The  opinions  put  forth  here  are  found  to  be  strikingly  coincident  with  those 
of  the  Chief  Commissioner  of  the  Levees  of  Mississippi.  His  Report  for  1856,  to 
the  Legislature  of  that  State,  has  just  been  brought  under  the  notice  of 
the  writer  of  this,  and  presents  an  opportunity  for  tho  endorsement  of  the  views 
given  under  the  above  head,  as  in  the  following  extract  from  that  Report  by  so  well- 
informed  and  judicious  an  observer : 

"The  practical  results  of  the  law  placing  the  direction  of  the  Levee  within  the 
respective  limits  of  each  County  on  tho  river,  in  the  hands  of  a  Board  constituted  on 
the  principle  of  local  representation,  have  been,  so  far  as  those  results  have  fallen 
under  my  observation,  decidedly  unfavorable  to  the  law.  The  act  substituting  a  sin- 
gle Commissioner  for  these  Boards  of  Commissioners  in  Tunica  and  Coahoma, 
has  worked,  in  my  opinion,  much  more  advantageously  to  the  interests  of  the 
Levee. 

"  This  individual  management  is,  in  truth,  in  more  close  conformity  with  the  phy- 
sical principle  that  should  direct  legislation  in  this  great  practical  work.  No  mere 
municipal  line  can  divide  an  interest  which  is  declared  one  and  indivisible  by  the 
eternal  law  that  rolls  out  the  floods  of  the  Mississippi  in  an  unbroken  whole.  In 
not  only  principle,  but  also  in  practice,  do  I  find  reason  to  recommend  this  system 
of  individual  control  in  the  design  and  construction  of  our  Levee.  It  went  into 
operation  in  the  County  of  Coahoma  two  years  ago,  receiving  from  the  previous  re- 


122  PRINCIPLES  AND   PEACTICE  OP 

cases  the  legislation  is  injudicious  in  its  working — in  Arkansas 
and  Louisiana  less  so,  however,  than  in  Tennessee,  Missouri,  and 
Mississippi.  The  latter  States  presenting  the  extreme  form  of 
objection  to  non-conformity  of  Levee-law  with  Levee-require- 
ment, the  following  remarks  on  points  of  this  non-conformity  are 
confined  to  the  legislation  of  those  States.  The  experience  that 
has  lead  to  the  preparation  of  these  remarks,  has  been  acquired 
in  Arkansas,  and  in  Mississippi ;  and  as  the  latter  is  one  of  the 

gime,  the  legacy  of  a  wasted  resource,  an  exhausted  treasury,  an  unsettled  indebt- 
edness, an  imperfect  record,  an  insufficient  and  incomplete  Levee,  and  last,  but 
worst  of  all,  an  almost  total  wreck  of  public  confidence  in  any  municipal  adminis- 
tration. But  what  now,  in  two  short  years,  is  the  condition  of  those  affairs  7  Though 
I  discuss  a  principle  only  in  this  case,  it  is  not  for  me  to  answer,  nor  is  my  answer 
necessary  when  the  answer  has  been  already  given  in  general  terms  by  the  County. 
This  principle  of  individual  management  in  carrying  out  our  Levee  has,  in  a  direct 
issue  with  the  principle  of  divided  management,  been  endorsed  emphatically  by  the 
intelligent  people  of  Coahoma.  Aware  that  the  unity  of  the  Levee  could  not  be 
broken  by  municipal  divisions,  I  had  the  honor  to  bring  forward,  two  years  ago,  the 
existing  law,  giving  a  general  jurisdiction  over  the  Levee  to  the  '  Superior  Board  of 
Levee  Commissioners.'  The  working  results  of  this  law  have  fallen  short  of  the 
physical  principle  which  was  sought  to  be  reached  by  it.  The  interest  of  the  river 
Counties  is  in  truth  such  a  perfect  unit  in  reference  to  the  Levee,  more  or  less  diffi- 
culty will  always  be  found  in  carrying  out  so  absolute  a  unity,  under  even  the 
strongest  organization  of  independent  jurisdiction.  A  breach  in  the  Levee  at  the 
upper  end  of  Issaquena  County,  would,  in  the  event  of  overflow  through  that  breach, 
cause  the  destruction  of  property  in  the  County  of  Washington  by  back-water.  An 
overflow  through  the  Levee  at  the  lower  line  of  Bolivar  County,  while  it  may  do  very  lit- 
tle damage  in  Bolivar,  may  spread  out  one  great  sheet  over  the  length  and  breadth  of 
Washington  County.  In  Tunica,  an  active  caving  of  the  river  bank  has  already  ad- 
vanced within  some  fifty  yards  of  the  Levee,  and  still  advancing,  the  next  flood  in 
the  Mississippi  will,  in  all  probability,  break  in  an  immense  volume  into  Eagle  Lake. 
Now,  to  the  greater  portion  of  the  people  of  Tunica,  this  result  is  a  matter  of  com- 
parative indifference — whereas  the  outfall  from  Eagle  Lake,  being  Southwardly  and 
Westwardly,  such  a  result  will  spread  devastation  far  and  wide  in  Coahoma ;  so  the 
construction  of  the  Levee  in  the  Southern  border  of  De  Soto,  is  a  matter  to  the  peo- 
ple of  that  County  of  comparative  indifference — the  majority  interest  is  already  pro- 
vided for — the  Levee  is  left  open,  and  the  country  South  of  them  becomes  the  suf- 
ferer. The  local  administration  is  the  supreme  power  over  that  portion  of  the  river 


EMBANKING  LANDS  FROM  EIVER-FLOODS.  123 

States  whose  Levee-legislation  illustrates  its  conflict  with 
Levee-expediences  most  forcibly,  it  is  therefore  selected  here 
to  illustrate  that  fact  by  examples  mainly  special  to  itself.  The 
conclusions,  however,  though  drawn  to  some  extent  for  special 
instances,  are  general  in  their  application — to  those  States  where 
Levee-administration  is  distended  to  the  extent  of  a  whole 
State,  and  also  to  those  where  it  is  narrowed* down  to  the  limits 
of  a  County. 

Drainage-legislation  is  based  on  error  in  limiting  the  admin- 

within  the  limits  of  De  Soto.  Tunica  has  not  the  protection  of  a  representation  of 
the  common  interest  which  is  bound  up  in  the  Levee  an  indivisible  unit.  Again, 
the  Leveeing  of  those  heads  of  Sunflower  which  traverse  Lewis'  Swamp,  in  tho 
County  of  Coahoma,  is  a  work  of  secondary  concern  to  the  great  majority  of  the  peo- 
ple of  that  County,  but  though  situated  within  a  jurisdiction  regarding  it  with  com- 
parative indifference,  this  part  of  the  Levee  is  of  much  deeper  importance  to  the 
upper  portion  of  Bolivar,  than  any  like  distance  of  low  bank  on  her  own  front. 
While  Coahoma  required  outlays  at  other  points  of  much  more  urgency  to  her  safe- 
ty, her  resources  have  naturally  been  employed  at  those  points  to  the  consequent 
injury  of  an  immense  amount  of  property  in  a  neighboring  jurisdiction. 

"  Indeed,  such  has  been  the  interest  felt  in  Bolivar  in  regard  to  this  Levee,  that 
influential  citizens  of  that  County,  had  offered,  in  addition  to  the  only  resources 
which  Coahoma  could  agree  to  apply  to  that  purpose,  to  pay  a  large  bonus  to  any 
contractors,  who  would  bind  themselves  in  a  contract  with  Coahoma,  to  Leveo 
Lewis'  Swamp.  But,  if  a  flood  shall  have  risen  before  this  swamp  is  Leveed,  under 
the  present  state  of  affairs,  how  bitterly  will  the  people  of  Bolivar  regret,  that  while 
the  local  interests  in  tho  Levee  have  been  provided  for  by  an  authority  and  an  ad- 
ministration, there  is  no  head,  no  strong  individuality  of  general  management,  to 
represent  the  strong  individuality  of  general  interest.  Wise  legislation  on  practical 
improvements  must  always  conform  to  physical  laws.  A  general  controlling  authority 
is  necessary  also  in  this  point  of  view,  to  represent  the  great  and  wide  considerations 
involved  in  the  intelligent  design,  and  the  straightforward  independence,  required 
in  the  faithful  execution  of  that  design,  from  end  to  end  of  that  great  physical  unit, 
the  Levee  of  the  Mississippi  and  Yazoo  bottom.  From  the  commencement  of  the 
system,  I  have  sought  to  convince  the  Levee  interest  of  the  necessity  of  this  individ- 
uality ;  thus  far  my  efforts  have  been  unavailing.  The  plan  of  operation  is  one  that 
I  have  never  approved.  I  have  been  driven  to  its  support  for  the  reason,  that  no 
other  plan  could  be  suggested  which  could  command  the  united  support  of  the  in- 
terests involved." 


124  PRINCIPLES   AND   PEACTICE  OF 

istration  under  it  by  arbitrary  lines.  In  Shelby  County,  Ten- 
nessee, the  proper  administration  of  the  Levees  is  not  placed 
under  the  guarantee  of  any  considerable  interest.  Some  eight 
or  ten  thousand  acres  of  swamp  subject  to  the  overflows  of 
Nonconnah  Creek  and  Horn  Lake  must  always  constitute  an 
insufficient  interest  for  the  enforcement .  of  an  independent 
administrator  of  the  Drainage-works  of  that  area  in  the  con- 
struction, protection,  and  maintenance  of  the  Levees  under  his 
control — Levees  extending  to  a  length  of  some  15  miles.  In- 
deed a  question  presents  itself  this  moment  as  to  whether, 
within  the  section  referred  to,  there  exists  a  single  plantation, 
there  resides  permanently  even  a  solitary  squatter.  The  fact 
is,  the  Leveeing  of  the  tract  in  question  cannot,  in  all  likeli- 
hood, be  said  under  existing  legislation  to  be  the  business  of 
any  one  ;  but  even  if  it  be  the  business  of  any  one,  the  area  to 
be  enclosed  does  not  present,  in  all  probability,  the  ways  and 
means  for  raising — does  not  in  short  present  a  sufficient  induce- 
ment to  justify — the  considerable  expenditure  required  for  its 
embankment — a  sum  that  cannot  be  less  than  some  $30,000. 
And  yet,  if  this  part  of  the  bottom  be  left  unenclosed,  the  whole 
Levee  from  the  Tennessee  line  to  the  Yazoo,  can  be  saved  from 
utter  uselessness  for  the  drainage  of  the  Valley  but  by  a  special 
work  pressing  on  the  limited  resources  of  the  Levee-interesis  in 
De  Soto  !  If  a  physical  facility  have  not  brought  this  special  em- 
bankment within  the  limits  of  the  ability  of  De  Soto,  the  inun- 
dations from  Horn  Lake  will  ignore  the  hamperings  of  Ten- 
nessee and  Mississippi  legislation  by  forcing  combined  action  of 
all  the  counties  between  the  Nonconnah  and  the  Yazoo,  in  the 
construction,  protection,  and  maintenance,  of  either  a  general 
Levee  from  the  Tennessee  line  to  the  Nonconnah  hills,  or  of  a 
special  embankment  in  De  Soto  County  from  the  existing 
River-Levee  to  the  Coldwater  high  lands.  But  instances  of  the 
bad  adaptation  of  the  present  law  are  numerous.  In  Tunica 
County,  Mississippi,  the  Commissioner  is  charged  with  several 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  125 

Keys  of  the  drainage  of  Coahoma,  Sunflower,  Tallahatchee — that 
at  Buck  Island  Bayou,  that  at  Couple-Timber  Bayou  &c.  These, 
however,  it  may  be  said  are  Keys  also  to  the  Drainage  of 
Tunica  itself ;  and,  therefore,  are  their  safe-keeping  placed  in 
the  hands  of  the  local  Commissioners  under  some  guarantee. 
Tunica,  however,  is  charged  with  another  Key  to  the  Drainage 
of  Coahoma,  Sunflower,  and  Tallahatchee — the  Levee  immedi- 
ately covering  the  plantations  on  the  North  shore  of  Moon  Lake. 
This  latter  Levee  protects  little  or  none  of  the  settlements  in 
Tunica  ;  whereas  the  flood-water  rushing  through  a  crevasse 
therein  sweeping  southwardly  across  Moon  Lake  and  the  Yazoo, 
will  inundate  the  fields  and  homesteads  of  Tallahatchee,  Sun- 
flower, and  Coahoma.  Want  of  interest  in  its  construction,  want 
of  funds  to  pay  for  that  construction,  demands  on  their  treasury 
and  attention  at  points  of  concern  to  themselves,  may  lead  the 
people  of  Tunica  at  any  moment  to  regard  this  Key  to  the 
Drainage  of  Coahoma  and  its  adjoining  counties,  with  a  very 
natural,  and  indeed  quite  excusable  neglect.  The  most  vital 
interests,  then,  of  Coahoma,  Sunflower,  and  Tallahatchee,  are 
placed,  by  the  system  of  County-jurisdiction  in  Leveeing, 
beyond  the  control  of  these  counties — placed  in  the  hands  of  parties 
who  can  afford  without  loss,  to  regard  the  protection  of  those 
interests  with  indifference.  A  tax  to  be  collected  from  them- 
selves for  the  construction  or  repair  of  the  Levee  covering  Moon . 
Lake — protecting  Coahoma — would,  naturally  enough,  be  not 
carried  probably  without  some  effort  amongst  the  people  of 
Tunica.  But  the  lower  Counties  show  the  working  of  the 
system  of  local-jurisdiction  in  still  more  objectionable  lights. 
In  Coahoma  County  there  may  be  said  to  be  no  settlement 
south  of  Lewis'  Swamp.  The  Coahoma  people,  as  a  body,  care 
very  little  therefore,  about  the  Leveeing  of  Lewis7  Swamp  ; 
whereas,  the  floods  breaking  through  that  swamp,  may  at  any 
time  after  the  failure  of  its  Levee,  inundate  at  even  ordinary 
floods,  the  lands  and  homes  of  Bolivar  and  Sunflower,  unless 


126  PRINCIPLES  AND  PEACTICE    OP 

Levee-jurisdiction  be  regulated  by  some  limits  more  practical 
in  their  operation  than  those  of  arbitrary  lines.  The  hampered 
workings  of  Levee-legislation  are  thus  seen  by  a  few  illustra- 
tions to  be  unjust  and  unsafe  for  the  whole  Valley  of  the  Yazoo — 
for  De  Soto,  for  Tunica,  for  Coahoma,  for  Bolivar,  for  Sunflower, 
for  Tallahatchee,  and  (the  contingencies  of  local  indifference, 
local  urgencies,  and  local  taxation,  accumulating  unfavorably  as 
the  testing  of  this  legislation  is  carried  down-stream)  the  injus- 
tice and  unsafety  is  still  greater  in  Washington  than  in  Bolivar  ; 
and  as  compared  with  Washington  is  still  greater  in  Issaquena. 
But  what  is  the  remedy  for  the  evils  of  the  present  system 
of  Levee-government?  An  extension  of  Levee-jurisdiction 
according  to  certain  physical  proprieties.  Working  necessities 
point  clearly  to  the  removal  of  the  existing  limits  on  the  ad- 
ministration, in  the  State  of  Mississippi,  of  river  embank- 
ments. The  location  considerations  referred  to  above,  operate 
in  full  force,  whether  or  not  the  ground  lie  one-half  in  Wash- 
ington, the  other  half  in  Issaquena.  In  locations  so  circum- 
stanced the  surveys  to  be  made  must  be  common  to  both  counties. 
The  flood-level  too,  is  a  subject  of  inquiry  that,  as  shown  above, 
cannot  be  cut  short  by  a  mere  legislative  fiction  ;  and,  here, 
again,  is  another  point  in  which  the  practical  duties  of  Levee- 
administration  ignore  the  system  of  imaginary  limits  to  Levee- 
jurisdiction.  Other  considerations  point  still  more  forcibly  to 
the  necessity  of  seeking  some  new  boundaries  for  the  limita- 
tions proper  to  that  jurisdiction.  Bolivar's  voice  and  Sunflow- 
er's voice  in  the  appointment  of  the  Commissioner  directing 
the  Levees  of  Coahoma,  will  guarantee  the  construction, 
protection,  and  maintenance,  of  a  Levee  across  Lewis'  Swamp, 
quite  as  soon  and  quite  as  surely,  as  that  across  the  Yazoo 
Pass,  or  at  any  other  point  in  Coahoma.  So  also  as  between 
Coahoma  and  Tunica  :  *  give  Coahoma,  Tallahatchee,  Sun- 

*  The  joint  interest  of  conterminous  counties  in  the  proper   administration  of 
their  respective  Levees  and  in  the  making  and  skill  of  their  respective  surveys,  is 


EMBANKING   LANDS  FROM    RIVER-FLOODS.  127 

flower,  voles  in  the  election  of  the  administrator  of  Levees  in 
Tunica  ;  and  Coahoma,  Tallahatchee,  Sunflower,  will  assuredly 
be  thereafter  saved  from  the  dangers,  the,  perhaps,  ruinous  in- 
difference that,  under  the  present  law,  may  at  any  moment 
inundate  their  hearths  and  fields  by  overflows  discharged  upon 
them  in  desolating  volumes  through  Moon  Lake.  But  what 
distribution  of  jurisdiction  will  conform  best  to  the  practical 
and  social  considerations  entering  into  Levee-administration  ? 
From  Cape  Girardeau  in  Missouri,  where  the  highlands  abut 
upon  the  river,  to  the  mouth  of  the  St.  Francis  in  Arkansas, 
where  the  back-drainage  of  the  intervening  country  must  be 
discharged,  defines  a  Levee-district,  which,  bound  together  by 
a  community  of  interest,  is  for  all  the  purposes  of  proper 
Levee-administration,  an  absolute  unity.  From  Sterling  in 
Arkansas,  at  the  mouth  of  the  St.  Francis,  where  the  Levee 
rests  on  the  slopes  of  Crowley's  Ridge,  to  the  mouth  of  White 
River,  where  the  back-drainage  of  the  intervening  country 
discharges,  is  also,  so  far  as  the  Mississippi  Levees  are  concern- 
ed, a  unit  in  Levee-interest ;  and,  therefore,  should  be  a  unit 

pointed  out  by  inference  in  the  following  remarks  of  Judge  Hardeman,  as  Levee- 
Commissioner  to  Tunica  County :  "  The  object  of  making  this  survey  was,  with 
the  then  indication  of  the  active  caving  of  the  bank  of  the  Kiver  at  the  Southern 
part  of  Trotter's  Field,  to  ascertain  whether  for  the  protection  of  the  back-country, 
we  would  be  compelled  to  Levee  around  Eagle  Lake.  *  *  *  The  indication  of  cave, 
&c.,  which  may  save  this  county  and  Cbahoma  a  considerable  amount  of  money,  &c. 
The  question,  however,  as  to  whether  we  go  around  Eagle  Lake  ought  to  be  deter- 
mined by  concert  of  action  between  the  Levee  Commissioners  of  Tunica  and 
Coahoma,  as  they  may  decide  as  to  the  best  interests  of  the  two  counties ;  for,  as 
before  remarked,  there  is  a  common  interest  of  the  two  counties  in  erecting  a 
Levee  across  the  Pass,  &c."  Report  for  1856,  page  5.  This  extract  specifies  an 
instance  in  which  the  location  of  a  Levee  in  one  Levee-jurisdiction  is  held  to  involve 
a  loss  or  a  gain  of  a  "  considerable  amount"  of  money  to  the  tax-payers  of  another 
Levee-jurisdiction ;  and  specifies  also  an  instance  in  which  the  construction  of  a 
Levee  within  one  jurisdiction  is  considered  to  be  a  question  of  drainage  within 
another  jurisdiction.  And  the  parties  thus  concerned,  in  the  one  case  in  their 
pockets  and  in  the  other  case  in  their  property,  to  be  deprived  of  all  influence  in 
making  that  location,  or  in  expediting  that  construction. 


128  PRINCIPLES  AND  PRACTICE  OF 

in  Levee- administration.  From  Pine  Bluff,  the  nearest  escarp- 
ment to  the  Mississippi  of  the  Arkansas  Uplands,  to  the  mouth 
of  Red  River  in  Louisiana — the  outlet  of  the  rain-shed  of  the 
intervening  bottom  lands — the  community  of  interest  in  the 
inclosing  Levee  is  so  indissoluble  that  the  proper  administration 
of  that  Levee  over-riding  all  imaginary  boundaries — whether 
of  County  or  of  State — must,  in  furtherance  of  sound  policy 
and  capable  management,  be  centered  of  necessity  in  one  and 
the  same  intelligence.  On  the  Eastern  bank  it  has  already 
been  indicated  sufficiently  plainly,  that  the  Levee-interests  from 
the  base  of  the  hills  below  Memphis  in  Tennessee  to  the  mouth 
of  the  Yazoo  River — the  debouch-channel  of  the  back-drainage 
of  the  included  area — is  so  thoroughly  identical  in  its  drainage 
affairs — socially  and  practically — that  the  administration  of 
those  affairs  within  that  area  has  been  described  by  Col.  Alcorn, 
most  correctly,  as  "  one  and  indivisible."  The  natural — the 
social  and  the  working — definitions  of  the  remaining  jurisdid- 
tions  in  Louisiana  and  in  Mississippi,  may,  with  the  views 
presented  above,  be  determined  by  those  acquainted  with 
the  physics  of  those  sections  ;  and  so  also  of  the  jurisdic- 
tions in  Tennessee,  Missouri  and  Illinois.  The  limits  as- 
signed the  districts  defined  here  are,  it  ought  to  be 
observed,  those  on  their  Mississippi  front,  the  limits  on 
their  inland  side,  in  each  case  being  located  as  hereafter 
indicated  on  such  lines  as  may  be  necessary  for  the  equal  dis- 
tribution of  Levee  taxation.  Sufficient,  however,  has  been 
said  here  to  show  that  physical  considerations  applied  socially 
and  practically,  while  ignoring  the  existing  limits  to  Levee-ad- 
ministration, describe  plainly  certain  limits  demanded  for  its 
efficiency.  * 

*  Some  four  years  ago  the  grounds  taken  here  were  taken  by  Col.  Alcorn,  see  note 
to  page  121,  in  urging  the  consolidation  of  Levee-government  in  his  Report  as 
chairman  of  the  Superior  Board  of  Levee- Commissioners,  to  the  then  Legislature  of 
Mississippi.  Tho  essential  unity  of  Levee-management  was  suggested  subsequently 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  129 

Unity  of  interest  can  be  served  truly  by  only  administrative 
unity.  Each  Drainage  District  then  (as  the  united  areas  referred 
to  above  may  be  termed,)  ought  to  be  placed  under  a  single 
administrator.  One  Commissioner  should  be  charged  with 
the  direction  of  drainage  embankments  from  Cape  Girardeau 
to  the  mouth  of  the  St.  Francis  ;  one  from  the  mouth  of  the  St. 
Francis  to  that  of  Arkansas  River  ;  another  from  Pine  Bluff  to 
the  mouth  of  Red  River.  On  the  opposite  side  a  single  Commis- 
sioner should  be  charged  with  the  control  of  the  Levee-interests 
from  the  Nonconnah  to  the  debouch  of  the  Yazoo.  But  while 
the  social  and  the  practical  considerations  in  the  case  conspire 

by  Judge  Hardeman,  Levee-Commissioner  of  Tunica  in  his  report  for  1856,  to  his  fellow 
commissioners,  Messrs.  E.  B.  Bridges  and  J.  A.  Cole,  in  the  following  judicious  re- 
marks :  "  The  propriety  of  this  repeal  may  be  a  question  of  doubtful  policy,  as  it 
must  be  apparent  to  you  that  a  common  interest  in  the  Levees  fronting  all  the  counties 
on  the  Mississippi  Eiver  from  Horn  Lake  to  the  mouth  of  Yazoo  River  ought  to  be  ap- 
preciated by  all  land-holders  within  that  Delta  formed  by  Coldwater,  Tallahatchee, 
and  Yazoo  Rivers,  to  its  entrance  with  the  Mississippi,  a  distance  of  350  miles,  em- 
bracing a  part  of  the  County  of  De  Soto,  all  of  Tunica,  Coahoma,  Bolivar,  Washing- 
ton, Issaquena,  Sunflower,  and  part  of  the  counties  of  Warren,  Yazoo,  Tallahatchee, 
and  Pauola,  *  *  *  Tunica  County  tax-payers  on  lands  bordering  on  Cold- 
water,  are  as  much  interested  in  the  Leveeing  around  Horn  Lake,  De  Soto  County, 
as  they  are  in  the  Levee  of  their  own  County  fronting  the  Mississippi  River ;  also 
the  land-owners  bordering  on  the  Mississippi  River  and  Coldwater  are  equally  inter- 
ested in  Leveeing  the  Yazoo  Pass  in  Coahoma,  as  the  water  in  making  its  way 
through  the  Pass  backs  up  through  Moon  Lake,  &c.,  to  the  town  of  Austin  and  its  vicin- 
ity. The  question  may  be  well  asked :  can  this  common  interest  in  the  Levees  on  the  river 
be  carried  on  without  concert  of  action,  $c."  Messrs.  Hardeman,  Bridges,  and  Cole,  are 
gentlemen  of  intelligence,  of  practical  acquaintance  with  the  working  of  the  Levee 
system ;  and,  as  such,  their  testimony  to  the  fact  of  Levee-unity,  so  far  as  it  goes,  is 
highly  valuable.  The  remarks  in  the  above  extract  point  to  the  restoration  of  the 
Superior  Board  of  Commissioners  as  fulfilling  all  the  suggestions  of  Levee-concert ; 
but,  loose  and  scattered  in  its  parts,  the  action  of  that  Board  lias  already  been  found 
to  be  utterly  inefficient.  Some  other  form  of  government,  therefore,  must  be  in- 
stituted to  meet  the  universally  accepted  fact  of  Levee-unity ;  and  the  form  of  a  gen- 
eral Board  having  been  tried  and  found  wanting,  the  necessities  of  the  moment 
point  to  the  only  practical — indeed  the  only  untried — form  remaining,  that  of  admin- 
i  strati ve  individuality. 


130  PRINCIPLES   AND   PRACTICE   OP 

to  define  the  working  limits  of  District  Levee-jurisdictions,  the 
practical  considerations  point  to  a  conclusion  still  in  advance  of 
existing  systems.  The  working  expediences  involved  in  capable 
administration  of  Levee-drainage  are  not  confined  to  one  side  of 
the  Mississippi.  The  comparison  of  High  Water  data  obtainable 
on  the  East  bank  with  that  obtainable  on  the  West  bank,  has 
been  referred  to  as  an  expediency  in  determining  the  question 
of  High  Water  Mark.  This  comparison,  then,  indicates  the  ex- 
tension of  District-administration  to  an  administration  of  wider 
scope  and  more  general  duties.  The  necessity  of  full  know- 
ledge of  the  location-facts  on  the  opposite  side,  and  of  certain 
accord  between  the  locations  on  both  sides,  is  another  instance 
under  a  system  of  District-management  of  a  commingling  that 
leads  plainly  to  a  further  widening  of  administrative  commu- 
nity. A  fusion  of  District  units  is  an  expediency  on  these 
grounds  ;  and  therefore,  on  the  further  ground  that,  only  by 
such  a  fusion  can  the  Levee-interest  of  the  great  Valley  of  the 
Mississippi  receive  the  first  great  contribution,  the  prime 
essential,  of  a  broad,  capable  administration — a  full,  correct  and 
connected  set  of  working  maps.  The  scientific  and  practical 
conditions  of  the  drainage  of  the  Yalley  by  Levees  require, 
therefore,  that  the  administration  of  each  Drainage  District  to 
the  full  extent  of  its  natural  limits,  be  placed  in  the  hands  of 
an  individual  Commissioner  ;  and  further  require  that  the  admin- 
istration of  all  joint-duties  of  the  Drainage  Districts  on  both 
sides  of  the  river,  be  placed  in  the  hands  of  those  individual 
Commissioners  assembled  in  general  Board  or  Council.  Legis- 
lation based  on  the  system  of  administration  sketched  out 
here,  is  clearly  the  only  one  adapted  to  the  direction  of  those 
important  works  under  the  lights  of  scientific  principle,  of 
practical  forethought,  of  sound  economy. 

Great  difficulties,  however,  obstruct  the  effective  working 
of  proper  machinery  for  the  management  of  Mississippi  Levees. 
The  popular  intelligence  holding  the  purse-strings  of  the  system 


EMBANKING  LANDS   FROM  RIVER-FLOODS.  131 

does  not,  in  some  cases,  go  to  the  extent  of  recognizing  in 
Leveeing,  any  skill  beyond  that  of  its  own  crude  observation. 
It  sometimes  commits  the  mistake  of  ignoring  the  existence  of 
centres  of  special  knowledge,  whether  in  Medicine  or  in  Engi- 
neering. Col.  Alcorn  has  been  constantly  hampered  in  his 
Commission  by  this  condition  of  public  opinion.  "  Such,"  he 
says,  in  his  last  pamphlet,  "  is  the  disposition  to  economise, 
that  complaints  are  made  should  the  Commissioner  employ  an 
Engineer  at  a  salary  of  fifteen  hundred  a  year  !  The  subject 
must  be  elevated  above  this,  or  decent  men  will  cease  to  be 
connected  with  it."  Laughable  as  such  difficulties  to  proper 
administration  as  those  indicated  in  this  extract  may  appear, 
they  present  in  practice  serious  embarrassment  to  intelligent 
and  vigorous  administration.*  His  intelligence,  his  personal 

*  One  of  the  embarrassments  to  the  Levee-reformer,  remaining  as  a  consequence 
of  the  former  employment  of  non-professional  men  for  Engineering  Levees,  presents 
itself  in  the  want  of  faith  amongst  even  intelligent  Planters  of  the  Valley,  in  the 
skill  and  independence  of  the  professional  Engineer.  Identified  widely  and  favor- 
ably, as  has  been  the  name  of  Mr.  M.  Butt  Hewson,  with  the  leading  measures  of 
public  improvement  in  the  South- West,  for  several  years — known,  as  it  is,  honorably 
to  the  professional  Engineer,  and  the  Railroad  public  generally,  from  New  York  to 
New  Orleans — the  Chairman  of  the  Board  of  Levee-Commissioners  for  the  State  of 
Mississippi,  was  obliged,  in  1855,  to  go  into  the  defence  hinted  at  in  the  following 
remarks  from  his  Report  of  that  year: — "The  Messrs.  Hewson,  both  M.  Butt,  the 
elder,  and  William,  the  younger,  are  Civil  Engineers  by  profession — have  been 
schooled  to  the  science — have,  by  competent  men,  been  heretofore  employed 
directing  some  of  the  most  important  public  works  of  the  South.  Their  labors  have 
passed  the  ordeal  of  severe  criticism ;  their  competence  has  not  been  disputed  by 
those  qualified  to  judge.  I  cannot  be  required  to  stop  and  argue  questions  with 
men  who  oppose  their  calculations — who  urge  in  opposition  thereto,  the  figures  of 
men  who  have  emerged  suddenly  from  the  walks  of  private  life,  for  convenience 
sake,  to  the  dignity  of  Civil  Engineers."  Sound  economy  demands  the  employment 
of  the  very  best  men  for  the  popular  and  for  the  professional  duties  of  the  Levee ; 
and  these  once  employed,  administrative  vigor  demands  that  they  be  treated  with 
the  fullest  confidence.  Disparagement  of  the  parties  entrusted  with  those  important 
duties,  will  merely  weaken  their  hands,  diminish  their  efficiency ;  and  ought  to  be, 
therefore,  frowned  down  by  the  intelligent  and  judicious,  unless,  when  based  on 


132  PRINCIPLES  AND    PRACTICE  OP 

pride,  his  honest  conviction,  and  his  whole  property  at  stake, 
on  the  success  of  the  Levees,  an  advanced  man  like  the  Com- 
missioner for  Coahoma  ought  not  to  be  met,  after  the  experi- 
ence of  the  public  in  those  works  for  fully  seven  years,  with 
narrow  and  silly  objections  to  his  employment  of  an  Engineer. 
Simple  as  thai  operation  of  shovelling  and  loosening  earth 
undoubtedly  is,  the  public  in  the  Yazoo  Valley,  have  not  yet 
realized  the  fact,  that  even  that  simple  operation  is  an  import- 
ant subject  of  practical  science.  Millions  of  dollars — national 
wealth,  and  national  advancement — at  stake  on  the  shovelling, 
loosening,  and  hauling  of  earth,  many  of  the  tax-payers  behind 
the  Levee  have  yet  to  learn,  or  to  value,  the  fact  that  even  this 
item  in  Leveeing,  taken  from  the  blind  guidance  of  the  rude 
and  wasteful  suggestions  of  uninformed  laborers,  has  been 
placed  under  the  infallible  guidance  of  economic  inductions 
incorporated  into  a  few  practical  laws.  Leveeing,  in  fact,  is  in 
every  particular  an  art.  It  requires  more  scientific  skill, 
patient  reflection,  careful  instrumentation,  and,  perhaps,  even 
more  prac^icalr*knOwledge  of  earth-works  and  foundations,  than 
-ilfrequired  in  the  Engineering  of  nine  out  of  ten  of  the  Kail- 
roads  of  the  country.  Besides  that,  the  Engineer  entering  on 
such-dutie^, /takes  the  position  in  his  profession  on  this  Conti- 
nent, of  the  pioneer  of  a  new  set  of  works,  the  classifier  of  a  new 
set  of  circumstances,  the  observer  of  a  new  set  of  phenomena  ; 
and  consequently,  to  be  professionally — that  is  to  say,  econom- 
ically— successful  as  such  pioneer,  classifier,  observer,  must  be 
guided  from  the  outset  by  all  the  lights  of  the  practice  of 
water-works  and  of  the  science  of  fluids.  Railroad  Engineering 
is  a  beaten  track.  Uniform  in  almost  all  its  details,  thatdepart- 
ment  of  the  profession  involves,  for  the  greater  part,  but  a 
mere  knowledge  of  routine  rules.  Routine  practice,  then,  will 
constitute  but  a  very  poor  qualification  for  a  position,  that  like 

unmistakable  grounds  that  may  be  followed  up  to  summary  dismissal.  No  unfit 
man  should  be  retained ;  no  fit  man  should  be— for  the  promotion  of  some  petty 
interest — damaged  in  his  efficiency. 


EMBANKING  LANDS  FROM  EIVER-FLOODS.  133 

Leveeing,  must  make  for  itself  its  own  rules  of  practice — rules 
that  cannot  be  made  by  ever  so  thorough  a  knowledge  of 
mere  routine,  unaccompanied  by  a  knowledge  of  the  principles 
of  practical  and  scientific  Engineering.  Thoughtful  intelligence, 
then,  appreciating  the  serious  interests  at  stake  in  the  effici- 
ency of  the  Levees,  instead  of  carping  at  the  placing  of  the 
professional  duties  of  the  Levee-system  in  the  hands  of  a  regu- 
larly trained  Engineer,  in  conjunction  with  the  most  able, 
enlightened,  and  honest  man  to  be  found  for  discharging 
the  popular  duties  of  the  system,  would  rather  have  suggested 
its  serious  apprehension  that  his  acceptance  of  a  salary  so 
small  as  $1500,  place  in  a  doubtful  light  the  professional  fit- 
ness of  the  Engineer  charged  with  duties  so  delicate  and 
responsible.  The  terrible  lesson  of  the  flood  just  subsiding, 
will,  however,  force  the  property  and  the  purpose  of  the 
great  Yalley  to  action — action  guided  by  all  the  lights  of  the 
broadest  and  most  liberal  intelligence.  It  is,  therefore,  hoped 
that,  in  order  to  sustain  this  expected  action,  some  steps  be 
set  on  foot  for  freeing  Levee-administration  from  the  popu- 
lar drawbacks  upon  its  efficiency,  by  either  raising  it  as  far 
as  is  practicable  above  local  restraints,  or,  failing  in  that,  by 
enabling  the  popular  intelligence  controlling  the  whole  sys- 
tem, to  keep  pace  with  the  growth  of  the  importance  of 
that  system.  * 

*  The  views  of  administration  presented  above,  have  been  endorsed  in  the  late 
message  of  Governor  McWillie,  of  Mississippi.  In  that  able  document,  his  Excel- 
lency holds  the  following  language : — "  This  is  a  matter  in  which  Mississippi  is  not 
alone  interested,  even  on  her  own  Levees.  All  tho  States,  above  and  below  her, 
along  the  river  bank  from  Cairo  down,  are  subject  to  the  same  inundation,  and  mu- 
tually act  and  react  upon  each  other.  The  Levees  of  any  one  State  are  parts  of  a 
chain  of  Levees  ;  and  the  direction,  restraints,  and  flow,  of  the  waters  of  the  Missis- 
sippi through,  or  past  any  State,  are  portions  of  the  forces  which  affect  its  regimen 
everywhere,  but  most  strongly  in  the  Counties  below.  *  *  *  No  elaborate  plea  is 
necessary  to  prove  the  importance  of  having  a  Levee-system  for  the  whole  Valley  of 
the  Mississippi,  framed  on  sound  principles  of  science,  and  in  concert  among  tho 
States  interested."  Change  of  administration — widening  and  concert  of  the  several 
existing  areas  of  administration — are  felt  on  all  hands  to  be  necessities,  and  the  best 
means  of  remedying  this  necessity  practically  is,  undoubtedly,  that  of  the  District 
Drainage  system  extended  to  the  organization  of  a  general  council. 


134  PRINCIPLES  AND   PRACTICE  OF 


CHAPTER    IX. 

EARTH     WORK      CALCULATIONS. 

The  Prismoidal  Formula  constitutes  the  only  rule  by  which 
regularly  sloped  embankments  can  be  measured  correctly. 
This  rule  is  as  follows  :  To  the  sectional  area  of  each  end  add 
four  times  the  area  of  the  middle  section  ;  one-sixth  of  the  result- 
ing sum  multiplied  by  the  length  of  the  prism,  gives  the  solid 
content.  If  lineal  yards  be  the  units  employed  in  the  calcula- 
tion, the  direct  result  of  the  rule  will  be  cubic  yards  ;  but  if 
lineal  feet  be  the  units  employed  in  the  calculation,  then  the 
direct  result  of  therule  being  cubic  feet,  must,  to  express  itself 
in  cubic  yards,  be  divided  by  27.  This  formula  supposes 
the  embankment  to  be  a  regular  prism ;  the  actual  height  of 
crown  and  width  of  base  midways  between  the  two  ends,  being 
the  arithmetical  mean — one-half  the  sum — of  the  corresponding 
heights  and  widths,  respectively,  of  the  two  ends.  The  end 
areas,  then,  must  never  exceed  such  limits  as  include  between 
them  observable  inequalities  of  ground — the  supposition  of 
the  rule  being  that  the  end  areas  have  been  taken  at  intervals 
sufficiently  close  to  have  broken  the  irregularities  of  the  work 
into  a  series  of  uniformly  sloping  prisms.  The  "  sectional 
area"  referred  to  in  the  rule  is  the  production  of  the  arithmet- 
ical mean — half  the  sum — of  the  width  of  crown  and  width  of 
base  by  the  height.  The  100  feet  chain  is  that  employed  by 
Engineers  in  order  by  taking  the  end  areas,  whenever  practi- 
cable at  that  distance  asunder,  to  simplify  the  above  prescribed 
rule  for  multiplying  by  the  length.  This  multiplication  in  the 


• 


EMBANKING  LANDS  FROM  EIVER-FLOODS.  135 

case  of  stations  100  feet  asunder  is  made  by  removing  the 
decimal  point  two  figures  to  the  right ;  or  when  multiplying  a 
whole  number  by  the  addition  to  it  of  two '  cyphers.  Lineal 
feet  being  generally  the  unit  of  measurement,  the  prismoidal 
formula  involves  in  general  a  division  by  27  to  reduce  its  result 
to  cubic  yards  ;  and  as  it  involves  also  a  previous  division  by 
6,  it  is  somewhat  of  an  abridgment  when  working  it  out  in 
detail  to  divide  the  sum  of  the  end  areas  and  four  times  the 
middle  area,  after  removing  the  decimal  point  two  figures  to 
the  right,  by  162 — six  times  twenty-seven.  In  order  to  explain 
more  clearly  the  working  out  of  a  measurement  under  the 
prismoidal  formula,  let  it  be  required  to  calculate  the  number 
of  cubic  yards  in  a  regular  embankment  100  feet  in  length,  ten 
feet  high  at  one  end,  and  4  feet  high  at  the  other  end,  the 
crown  having  the  uniform  width  of  5  feet,  the  base  of  the  slopes 
being  proportional  to  the  height  as  six  to  one.  The  base  for 
the  end  10  feet  high  is  (six  times  10  for  the  slopes  and  5  feet  for 
width  of  crown)  65  feet ;  and  one-half  the  sum — the  arithmet- 
ical mean — of  the  width  of  base  and  width  of  crown  being 
(65  and  5  divided  by  2)  35,  the  product  of  the  arithmetical 
mean  by  the  height  (35  by  10)  is  350,  the  area  at  the  large  end. 
By  a  like  process  the  sectional  area  for  the  small  end  is 
68.  The  arithmetical  mean — one-half  the  sum  of  the  heights  at 
both  ends — is  (10  and  4  divided  by  2)  7 — the  height  of  the 
middle  section.  The  area  corresponding  to  this  height,  by  the 
calculation  explained  before,  is  182  ;  and  this  multiplied  by 
4  gives  a  product  of  728 — 4  times  the  middle  area.  350  (one 
end  area)  and  68  (the  other  end  area)  and  728  (4  times  the 
middle  area)  show  a  total  of  1146  ;  and  this  multiplied  by  the 
length  being  114600,  one-sixth  of  the  product  divided  by  27  (or 
114600  divided  by  162)  shows  a  quotient  of  707.40,  the  content 
of  the  embankment,  in  question,  in  cubic  yards.  To  explain 
this  more  clearly  it  is  better  to  repeat  the  same  calculation  in 
another  form  : 


136  PRINCIPLES   AND   PRACTICE   OF 

GREATER   END.  LESS   END. 

10  (height)  4     (height) 

6  rate  of  slope,  6    rate  of  slope, 

60  base  of  slopes,  24  base  of  slopes, 

5  base  of  crown,  5  base  of  crown, 

65  width  of  base,  29  width  of  base, 

5  width  of  crown,  5  width  of  crown, 

2)70  sum  of  widths,  2)34  sum  of  widths, 

35  arithmetical  mean,  or  half  the  17  arithmetical  mean,  or  half  the 

sum  of  the  width  of  crown,  sum  of  the  width  of  crown, 

and  of  base.  and  of  base. 

35  arithmetical  mean  width,  17  arithmetical  mean  width, 

10  height,  4  height, 

350  sectional  area.  68  sectional  area. 

MEAN    AREA. 

10  height  of  greater  end, 

4  height  of  less  end, 

2)14  sum  of  the  two  heights. 

7  mean  height. 

6  rate  of  slope, 

42  base  of  slopes, 

5  base  of  crown, 

47  width  of  base, 
5  width  of  crown, 

2)52  sum  of  widths, 

26  arithmetical  mean  or  half  the  sum  of 

the  width  of  crown  and  of  base. 
26  arithmetical  mean  width, 

7  height, 

182  sectional  area, 
4  multiplier, 

728  four  times  the  middle  area. 

SUMMATION. 

350  area  of  greater  end, 
68  area  of  less  end, 
728  four  times  middle  area 

1146  aggregate  of  areas, 
100  length, 

6)114600  product  of  aggregate  by  length, 
27)19100  content  in  cubic  feet, 
707.40  content  in  cubic  yards. 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  137 

This  then  is  the  full  detailed  method  of  earth-work  estimation 
in  accordance  with  the  prismoidal  formula.  Before  offering  any 
further  remarks  on  the  subject,  it  is  better  to  meet  here  the 
prevailing  practice  of  estimation  among  the  unskilled  men 
charged  with  the  "  Engineering"  of  Levees,  by  some  compari- 
sons with  the  above — the  correct — practice.  The  methods  of 
calculation  in  common  use  on  all  the  Levees  of  both  Arkansas 
and  Mississippi — with  the  exception  of  those  in  Coahoma, 
where  Col.  Alcorn  has  taken  the  trouble  to  acquire  perfect 
facility  in  the  correct  practice  himself — are  those  by  average 
heights  and  by  average  end  areas.  These  systems  are  wrong  in 
principle  ;  but,  in  the  popular  spirit  by  which  these  remarks 
have  been  guided,  waving  the  error  of  principle,  the  most 
effective  corrective  in  the  case  will  be  an  illustration  of  that 
error  in  practice.  The  prismoidal  formula  has  already  been 
worked  out  in  detailing  the  measurement  of  a  Levee  ten  feet 
at  one  end  and  four  feet  high  at  the  other  end,  the  width  of 
crown  being  uniformly  5  feet ;  and  the  aggregate  rate  of  side 
elopes  6  to  1.  The  content  of  this  embankment  will  now  be 
detailed  according  to  the  two  rules  of  measurement  pursued 
generally  on  the  Mississippi : 

BY  AVERAGE  HEIGHTS. 

10  height  at  greater  end,  182  area  for  average  height, 

4  height  of  less  end,  100  length, 

2)14  sum  of  heights,  27)18200  content  in  cubic  feet, 

7  average  height,  674.00    content  in  cubic  yards. 

6  rate  of  slope, 

BY  AVERAGE   AREAS, 

42  base  of  slopes, 

5  base  of  crown,  350  area  of  greater  end, 

68  area  of  less  end. 
47  width  of  base, 
5  width  of  crown,  2)418  sum  of  areas, 

2)52  sum  of  widths,  209  average  area, 

100  length, 
26  half  sum  of  widths. 

7  average  height,  27)20900  content  in  cubic  feet, 

182  area  for  average  height,  774.00  content  in  cubic  yards. 


138  PRINCIPLES  AND  PRACTICE  OP 

By  this  method  of  average  heights,  then,  the  solid  content  of 
the  embankment  in  question,  would  be  taken  at  674  cubic 
yards ;  and  by  the  method  of  average  areas  at  774  cubic  yards ; 
a  difference  that  at  fifteen  cents  a  yard,  showing  a  discrepancy 
of  $15  for  100  feet  of  Levee,  would  sum  up  at  the  same  rate  to 
an  immense  sum  when  repeated  for  every  100  feet  along  the 
whole  extent  of  even  a  County.  But  the  fact  of  the  case  is  ; 
both  of  the  quantities  are  wrong  ;  and  the  one — that  by  aver- 
age areas — being  wrong  in  its  excess,  is  an  injustice  to  the 
tax-payer,  while  the  other — that  by  average  heights — being 
wrong  in  its  deficiency,  is  an  injustice  to  the  contractor.  The 
true  quantity,  as  given  in  accordance  with  the  prismoidal  for- 
mula, has  been  shown  in  detail  to  be  707  cubic  yards.  The 
quack-systems  then,  and  the  correct  system,  compare  in  the 
case  under  consideration  as  follows  : 

674  cubic  yards — the  content  by  average  heights. 

707  cubic  yards — the  content  in  fact. 

774  cubic  yards — the  content  by  average  area. 

One  of  the  common  systems,  then,  of  calculation  by  average 
heights  is  an  injustice  in  the  instance  under  consideration,  at 
the  rate  of  $261  per  mile  to  the  Levee  contractor  ;  the  other 
and  equally  common  system  is  an  injustice  in  the  same  instance 
at  the  rate  of  $531  per  mile  to  the  Levee-tax-payer.  This 
assumes  the  cost  of  the  work  at  15  cents  per  cubic  yard.  The 
error  of  these  modes  of  calculation  are  sometimes  less  than  in 
the  case  presented  above  ;  but  they  are  also,  sometimes,  even 
still  greater :  with  end-areas  and  end-heights  nearly  equal, 
they  are  very  trifling  ;  but  with  end-areas  and  end-heights 
differing  largely,  those  errors  become  very  serious.  For  the 
width  of  crown  and  rate  of  base  adopted  in  the  above  exam- 
ple, the  excess  of  result,  according  to  the  system  of  average 
areas  for  example,  increases  over  the  true  content  of  the  prism 
according  to  the  following  gradations  :  for  lengths  of  100  feet, 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  139 

where    the  inequality  of  the   heights  of  the   two   ends  is/ 

1  foot,  the  excess  given  by  the  method  of  average  areas,  is        1.6  cubic  yards. 

2  feet,  do  do  7.5  cubic  yards. 

3  feet,  do  do  17.0  cubic  yards, 

4  feet,  do  do  30.0  cubic  yards. 

5  feet,  do  do  46.0  cubic  yards. 

6  feet,  do  do  66.6  cubic  yards. 

7  feet,  do  do  90.7  cubic  yards. 

8  feet,  do  do  118.5  cubic  yards. 

Adopting  still  the  five-feet  crown  and  six-fold  base,  the  insuffi- 
ciency of  the  quantities  resulting  from  the  process  of  average 
heights,  follows  the  following  gradations  :  with  a  length  of  100 
feet  where  the  inequality  of  the  heights  of  the  two  ends  is, 

1  foot,  the  deficiency  by  the  method  of  average  heights,  is        0.8  cubic  yards. 

2  feet,  do  do  3.7  cubic  yards. 

3  feet,  do  do  8.5  cubic  yards. 

4  feet,  do  do  15.0  cubic  yards. 

5  feet,  do  do  23.0  cubic  yards. 

6  feet,  do  do  33.3  cubic  yards. 

7  feet,  do  do  45.4  cubic  yards. 

8  feet,  do  do  59.3  cubic  yards. 

It  may  be  noted  here  that  the  calculations  by  average  Jmghts  are 
always  a  wrong  to  the  contractor ,  those  by  the  average  area 
being  always  a  wrong  to  the  public — the  deficiency  in  the  one 
case  being  one-half  that  of  the  excess  in  the  other  case.  But, 
bad  as  are  both  of  those  methods  when  applied  to  even  short 
lengths  of  embankment,  a  very  common  practice  in  the  use  of 
both,  by  extending  the  averages  to  considerable  lengths,  make 
the  evil  still  greater.  The  following  table  shows  the  heights, 
crown,  and  base  of  a  Levee,  taken  at  regular  intervals  of 
100  feet ;  extracted  from  a  measurement-book  of  my  own  prac- 
tice on  Levees,  it  represents  an  actual  state  of  facts.  The 
last  column  shows  the  content  of  each  100  feet  of  the  embank- 
ment, according  to  the  prismoidal  formula — the  true  content — 
in  cubic  yards. 


140 


PRINCIPLES  AND  PEACTICE    OF 


Stakes.         Heights. 

Widths. 

Contents  in 
cubic  yards 

Crown.  |       Base. 

1210 

3.36 

5 

20.16 



1211 

2.59 

5 

15.54 

124.9 

1212 

1.77 

5 

10.60 

74.3 

1213 

1.60 

5 

9.60 

47.5 

1214 

1.43 

5 

8.58 

39.2 

1215 

1.80 

5 

10.80 

43.7 

1216 

2.52 

5 

15.12 

71.8 

1217 

1.74 

5 

10.44 

71.4 

1218 

3.00 

5 

18.00 

85.0 

1219 

3.72 

5 

22.32 

156.1 

1220 

3.18 

5 

19.08 

164.5 

1221 

3.91 

5 

23.46 

173.6 

1222 

3.73 

5 

22.38 

196.4 

1223 

3.63 

5 

21.78 

186.3 

1224 

2.60 

5 

15.60 

137.1 

1225 

1.96 

5 

11.76 

79.9 

1226 

6.28 

5 

37.68 

243.0 

1227 

9.40 

5 

56.40 

7ti6.2 

1228 

7.58 

5 

45.48 

884-5 

1229 

12.38 

5 

74.28 

1225.1 

1230 

11.26 

5 

67.56 

1659.8 

1231 

8.69 

5 

52.14 

1207.8 

1232 

10.23 

5 

61.38 

1283.9 

1233 

8.66 

5 

51.96 

1082.2 

1234 

7.66 

5 

45.96 

814.4 

1235 

7.49 

5 

44.94 

704.7 

1286 

8.50 

5 

51.00 

786.1 

1237 

8.74 

5 

52.44 

003.1 

1238 

7.47 

5 

44.82 

805.6 

1239 

6.12 

5 

36.72 

577.1 

1240 

3.04 

5 

18.24 

285.3 

1241 

2.10 

5 

12.60 

97.2 

1242 

1.75 

5 

10.50 

60.0 

1243 

1.63 

5 

9.78 

47.9 

1244 

1.76 

5 

10.56 

47.9 

1245 

2.09 

5 

12.54 

60.0 

1246 

2.22 

5 

13.32 

71.4 

]247 

3.49 

5 

2C.94 

118.3 

12-18 

3.47 

5 

20.82 

167.9 

1249 

3.43 

5 

20-58 

164.4 

1250        I 

3.42 

5 

20-52 

160.7 

Total  cubic  yards,       ....  15,670.2 

The  true  content  of  the  above  Levee — 4,000  feet  long — was 
15676  cubic  yards.  Now,  the  average  height  of  all  the  stations 
on  this  piece  of  work  was,  as  may  be  seen  by  adding  up  the 
above  column  of  heights,  and  dividing  the  sum  by  the  number 
of  heights  so  added,  4.67  feet.  The  average  width  correspond- 
ing to  the  average  height,  being  16.51  feet,  the  area — the 
product  of  this  average  height  by  its  average  width — is  77.10 
square  feet.  To  repeat  this  in  another  form  : 

16.51  the  average  width  corresponding  to  a  height  of  4.67  feet. 
4.67  the  average  height  of  the  whole  embankment. 

77.10  the  average  area  by  a  general  average  height  of  the  whole  bank. 
4000  the  length  of  the  whole  bank. 


27)308400,  content  of  whole  bank  in  square  feet. 
11422.22,  content  of  whole  bank  in  cubic  yards. 


EMBANKING  LANDS  FROM  RIVER-FLOODS.  141 

The  comparison  in  this  instance  then,  stands  thus  : 

15672  cubic  yards,  the  true  content. 

11422  cubic  yards,  the  content  by  a  general  average  height. 

4250  cubic  yards  of  error  against  contractor. 

The  contractor,  in  this  instance,  paid  nominally,  15  cents  per 
yard  for  his  work,  would,  in  fact,  be  paid  according  to  this  sys- 
tem of  measurement,  at  the  rate  per  yard  of  less  than  11  cents. 
The  contractor,  however,  is  generally  able  to  secure  fair  play 
for  himself ;  but  in  the  case  of  those  methods  of  calculation 
that,  pursued  as  they  are  by  officers  of  the  public,  give  the 
contractor  a  large  excess  above  his  just  rights,  there  is  no  pro- 
tection to  save  that  public,  when  it  contracted  for  but  15  cents 
a  yard,  from  paying,  in  consequence  of  the  unfitness  of  its  own 
officer — its  "  Engineer"— so  high,  in  fact,  as  even  20  cents  a 
yard.  So  important  is  it  to  both  the  contractor  on  Levees,  and 
to  the  public  paying  for  their  construction,  that  a  system  of 
measurement  be  laid  down  that,  adapted  to  the  popular  under- 
standing., may  secure  to  both  parties  mutual,  even-handed 
justice.  .'  f  .  '  t  *r  J  ; 

The  errors  of  the  systems  common  in  measuring  Levees  thus 
exposed,  attention  may  be  now  recalled  to  the  prismoidal  rule. 
The  illustration  given  of  that  rule  willhave  suggested  that  its 
employment  at  intervals  of  100  feet,  and  of  less,  along  a  line-  of 
Levee,  makes  correct  estimation,  a  process  most  elaborate  and 
tedious.  Practice,  however  gives  a  surprising  expertness  in 
casting  up  quantities  directly  ;  and  also  in  the  use  of  regular 
forms  of  calculation,  suggests  from  time  to  time  several  meth- 
ods of  abridgement.  For  a  regular  rate  of  slope,  for  instance, 
the  Engineer  about  to  estimate  any  considerable  stretch  of 
work,  finds  it  much  more  correct  and  rapid  to  calculate,  in  the 
first  place,  a  regular  table  for  that  slope  ;  and  applying  that 
table  to  the  special  dimensions  of  his  measurement,  take  off 
prismoid  after  prismoid,  by  inspection.  For  new  Levees  such 


142  PRINCIPLES  AND  PRACTICE  OF 

a  table  is  directly  applicable.  Tables  1,  2,  and  3,  have,  accord- 
ingly, been  added  at  the  end  of  these  remarks,  for  the  use  of 
the  less  expert — and  indeed,  also,  of  the  more  expert — to  whom 
the  elaboration  necessary,  otherwise,  may  be  an  obstacle  to 
the  general  introduction  in  Levee-measurement  of  the  pris- 
moidal  formula.  These  calculations  are  intended  to  cover  all 
the  forms  of  section  prevailing  in  the  Levee-practice  of  the 
Mississippi.  In  terms  representing  cubic  yards,  the  tables 
show,  for  prisms  of  100  feet  long,  the  "  end  area,"  and 
"  four  times  middle  area"  for  all  heights  to  tenths  and  half 
tenths  of  a  foot,  from  a  height  of  one  foot  to  a  height  of  24.95 
feet.  Table  No.  1  is  estimated  for  a  base-width  of  6  feet  hori- 
zontal to  1  foot  vertical ;  and  with  a  crown  of  5  feet  wide — 
the  dimensions  allowed  by  the  Superior  Board  of  Levee 
Commissioners  for  the  State  of  Mississippi.  Table  No.  2  is 
estimated  for  a  base,  bearing  the  same  constant  proportion  to 
the  height ;  but  differing  from  table  No.  1  in  having  a  crown  of 
only  3  feet  wide.  No.  3  gives  the  quantities  under  the  same 
heads,  in  the  same  terms,  and  for  the  same  intervals,  for  a  Levee 
having  a  crown  of  3  feet  across ;  but  with  a  base  having  a 
width  of  seven  times  the  height.  The  dimensions  given  in  this 
table,  are  those  generally  used  in  the  State  of  Arkansas,  with 
the  exception  of  the  width  of  crown  ;  the  adopted  crown-width 
being,  as  before  remarked,  erroneous  in  principle.  In  measur- 
ing the  Levee  it  is,  in  fact,  not  practicable  to  arrive  at  a  greater 
accuracy  in  the  heights  than  a  tenth  of  a  foot.  The  tables  are 
accordingly,  in  being  extended  to  tenths,  carried  out  to  the  full- 
est detail  available  in  practical  estimation.  In  order  to  show 
in  juxta-position  a  calculation  made  in  detail,  and  the  same 
made  under  the  abridging  of  the  above  table,  let  it  be  proposed 
to  cast  up  the  quantities  in  a  Levee  100  feet  long,  3.60  feet  in 
height  at  the  less  end,  and  7.70  feet  in  height  at  the  greater 
end,  the  base  being  always  six  times  the  height,  and  the  crown 
of  the  uniform  width  of  5  feet. 


EMBANKING  LANDS  FROM  RIVER-FLOODS.                      143 

PRISMOIDAL  FORMULA  WORKED  OUT  IN  DETAIL. 

GREATER  END.  LESS  END. 

7.70  height,  3.60  height, 

6  multiple  for  base,  6  multiple  for  base, 

46.20  width  of  base,  21.60  width  of  base, 

6.00  width  of  crown,  5.00  width  of  crown, 

2)51.20  sum  of  width,  2)26.60  sum  of  width, 

25.60  mean — or  half  sum  of  width  13.30  mean — or  half  sum  of  width, 

7.70  height,  3.60  height, 

179200  79800 

1792  399 


197.1200  sectional  area.  47.8800  sectional  area. 

MIDDLE   AREA. 

7.70  height  at  greater  end. 
3.60  height  at  less  end, 

2)11.30  sum  of  heights 

5.65  mean — or  half  sum  of  heights, 
6  multiple  for  base, 

33.90  width  of  base, 
5.00  width  of  crown. 
2)38.90  sum  of  width. 


19.45  mean — or  half  sum  of  widths, 
5.65  mean  height, 

9725 
11670 
9725 

109.8925  middle  area. 

4  multiple  according  to  rule, 

439.57  four  times  middle  area, 
197.12  area  at  greater  end, 
47.88  area  at  lesser  end. 

6)68457  sum  of  areas, 

114.095  one-sixth  the  sum  of  areas, 
100  length. 

27)114095  (422.6  solid  content  in  cubic  yards. 
108 

60 
54 

69 
54 

155 

162 


144  PRINCIPLES  AND  PRACTICE  OP 

Such  is  the  regular  working  out  of  this  quantity  in  detail. 
Let  it  now  be  worked  out  by  the  tables.  The  crown  being  five 
feet  and  the  base  six  times  the  height,  the  table  to  be  employed 
in  the  case  is  No.  1.  Turning  then  to  No.  1,  under  the  head  of 
three  feet  and  on  the  line  corresponding  to  the  decimal  .60  in 
the  margin,  the  tabular  "end  area "  corresponding  to  3.60  is 
found  to  be  29.6 ;  under  the  head  of  7  feet  and  on  the  line  of 
the  marginal  decimal  .70,  the  end  area  in  the  table  is  121.7. 
Adding  together  3.60  the  height  at  one  end,  and  7.70  the  height 
at  the  other  end,  the  aggregate  is  11.30  ;  and  this  sum  divided 
by  2  shows  for  the  middle  height,  5.65  feet.  Turning  again  to 
the  table,  the  tabular  number  under  the  head  5  feet,  and  on  the 
line  .65,  is  found  in  the  column  of  "  middle  areas  "  to  be  271.4. 
Adding  271.4  (four  times  the  middle  area)  29.6  (the  area  at  the 
less  end)  and  121.7  (the  area  at  the  greater  end)  the  total  is 
422.7.  This  explanation  of  the  use  of  the  tables  thus  given,  the 
comparison  with  the  above  detail  may  be  now  commenced. 

3.60 — less  height — tabular  "  end  area"  corresponding,      -        -          29.6 
7.70 — greater  height — tabular  "  end  area"  corresponding,      -        -    121.7 

2)11.30  sum  of  heights. 

6.65 — middle  height — tabular  "  4  times  middle  area"  corresponding,    271.4 
Solid  content,  by  prismoidal  formula,  in  cubic  yards,    -    -      422.7 

The  figures  in  each  process  show  at  a  glance  the  facilities  fur- 
nished by  the  table — the  detail  process  requiring  208  figures, 
and  tabular  abridgement  but  29  figures.  The  tables,  then,  may 
be  held  as  reducing  the  time  and  labor  of  calculations  by  the 
prismoidal  formula  to  one-seventh  the  time  and  labor  neces- 
sary in  carrying  out  that  formula  in  detail.  These  tables  are 
altogether  new — the  result  of  using  the  formula  extensively 
when  cutoff  from  an  opportunity  of  reference  to  any  other 
system  of  calculation  by  inspection.  Original  in  every  partic- 
ular as  they  are,  it  is,  perhaps,  better  to  explain  more  fully 
than  has  been  done  in  the  foregoing  comparison,  the  use  and 


EMBANKING  LANDS  FEOM  RIVER-FLOODS. 


145 


convenience  of  those  tables.  Passing  to  this  explanation,  it 
may  be  observed  that  the  quantities  employed  in  the  table  are 
fictitious,  representing  no  real  quantity,  until  the  summation 
into  a  solid  content,  when  they  take  the  form  of  cubic  yards. 
Extracting  the  heights  at  each  station  from  the  level-book, 
these  are  transferred,  in  the  office,  to  the  measurement-book 
in  the  following  manner. — The  column  showing  the  distances 
between  the  several  stations  (see  annexed  form)  are  to  be  filled 
up  with  those  distances,  leaving  every  second  line  blank.  The 
heights,  respectively,  corresponding  to  those  distances  are 
then  transferred  to  the  column  of  heights,  each  opposite  its 
own  distance,  and  consequently  entered,  like  the  distances,  on 
every  second  line.  The  third  column  of  the  measurement-book 
is  next  filled  in  with  the  quantity  constituting  an  arithmetical 

Form  of  Measurement  Book  adapted  to  Tables  JSfos.  I.,  II.,  and  III. 


Distance 
Station. 

End 

Heights. 

Mean 
Heights. 

Tabular 

Number. 

Contents  in 
Cubic  Yards. 

Remarks. 

0 

100 
200 
300 
400 
500 
13  feet 

5.00 
5.20 
5.80 
5.80 
5.70 
7.20 
19.60 

5.10 

54.1 
224.2 
58.1 
258.0 
71.8 
262.4 
C0.2 
258.0 
69.0 
848.0 
107.1 
1412.8 
741.7 

836.4 
887.4 
893.9 
887.2 
624.1 
294.0 

58.1  belonging  to  this  pris- 
moid  is  included  therein, 
and  belonging  also  to  the 
following,  is  included  in 
that,  too. 

Special  calculation. 

5.50 
5.55 
5.50 
6.45 

13.40 

mean  between  each  pair  of  heights  entered  in  the  second  col- 
umn— this  mean  being,  of  course,  one-half  the  sum  of  its 
corresponding  pair  of  end-heights.  These  mean  heights  are 
entered  in  the  lines  that  had  been  left  blank,  when  filling  in 
the  first  and  second  columns  ;  and  thus  occupy,  in  the  mea- 
surement-book, a  place  between  the  two  heights,  from  which 
each  of  them  is  deduced.  The  end-heights,  and  mean  heights 
thus  filled  in  and  placed  in  proper  position  in  the  measure- 
ment-book, the  calculator  will  next  call  to  his  assistance  the 


146  PRINCIPLES  AND  PRACTICE  OF 

earth-work  tables.  In  doing  this,  it  must  be  recollected  that 
each  set  of  heights  in  the  tables,  having  corresponding  to  it 
two  different  sets  of  quantities — that  in  the  column  of  "  end- 
areas,"  and  that  in  the  column  of  "  4  times  the  middle  height' ' — 
the  only  certain  mode  of  guarding  against  the  use  of  one  of 
these  for  the  other,  is  to  first  take  out  the  quantities  under  one 
head — those  for  the  measurement-column  of '"end-heights,"  first  j 
and  all  these  completed,  then  take  out  the  quantities  under  the 
other  head — those  for  the  measurement-column  of  "  mean 
heights."  The  first  "  end-height,"  then,  is  5.00.  Turning  to 
table  No.  1,  the  eye  rests  on  the  head — in  large  characters — 
"  5  feet."  Running  down  the  margin,  the  decimal  "  00"  is 
seen  ;  and  the  "  end-areas"  under  the  heading  "  5  feet"  on  line 
"  00"  is  found  to  be  54.0.  Under  the  head,  Tabular  numbers 
of  the  measurement-book,  this  54.0  is  then  entered  on  the  line 
running  across  the  book  from  the  end-height  5.00.  The  head- 
ing "  5  feet,"  being  again  used  in  the  tables,  the  eye  rests  in 
the  next  place  on  the  marginal  decimal  .20  ;  and  the  "  end- 
area"  under  the  head  "  5  feet,"  corresponding  to  the  decimal 
.20,  is  seen  to  be  58.1.  The  58.1  is,  then,  entered  in  the  col- 
umn of "  tabular  numbers"  of  the  measurement-book,  on  the 
line  running  across  the  book  from  the  corresponding  height  of 
5.20.  So,  also,  with  all  the  other  "  end-heights."  These  com- 
pleted, the  next  duty  is  to  take  out  the  tabular  numbers  for 
the  "mean  heights."  These,  be  it  remembered,  are  found  in 
the  column  "  4  times  middle  area."  The  first  mean  height  in 
the  above  form  of  measurement-book,  is  5.10.  Again,  under 
the  head  "  five  feet,"  after  running  down  the  margin  to  the 
decimal  .10,  the  eye  rests  on  the  tabular  number  corresponding 
to  5.10  in  the  column  ';  4  times  the  middle  area."  This  num- 
ber is  seen  to  be  224.2.  Opposite  to,  and  on  the  line  running 
across  the  measurement-book  from,  "  mean  height"  5.10,  this 
number,  224.2  is  next  entered  in  the  column  of  tabular  num- 
bers. The  mean  heights  are  thus  gone  through,  one  after  the 


EMBANKING   LANDS  FROM   RIVER-FLOODS.  147 

other.  The  use  of  the  tables  ended,  the  next  step  is  the  sum- 
mation. This  must  be  done  by  grouping  together  each  three 
quantities  in  the  column  of  "  tabular  numbers" — always  taking 
care  that,  after  that  quantity  corresponding  to  the  first  distance 
the  quantity  corresponding  in  the  column  of  "  tabular  num- 
bers" to  each  distance,  or  to  each  "  end  height,"  shall  be  used 
in  the  additions  twice — once,  in  addition  to  the  two  quantities 
above  it,  and  again,  in  addition  to  the  two  quantities  l>dow  it, 
in  the  measurement-book.  The  column  "  content  in  cubic 
yards"  thus  made  out  for  each  distinct  prism,  the  addition  of 
oil  completes  the  measurement.  This  supposes  the  stations, 
it  will  be  observed,  separated  by  uniform  distances  of  100  feet 
each.  In  irregular  ground,  however,  the  stations  must  be 
separated  by  irregular  intervals — in  bayous,  for  instance,  it 
being  often  necessary  to  place  them  so  close  together  as  4  or 
5  feet.  The  measurement-book  in  such  cases  is  filled,  as  shown 
between  stations  4  and  5  in  the  above  form,  the  prisms  being 
made  subjects  of  special  calculations.  These  calculations  may 
be  made  with  a  saving  of  time  and  trouble  by  adding  the  tabu- 
lar numbers  corresponding  to  its  end-heights,  and  to  its  mean 
height  as  described  for  the  100  feet  lengths  ;  and  multiplying 
the  sum  of  these  numbers  by  the  length  of  the  short  prism  in 
question  ;  the  removal  of  the  decimal  in  the  product,  two  fig- 
ures to  the  left,  will  give  the  true  content  of  that  prism. 
Suppose,  for  illustration,  a  prismoid  of  13  feet  length,  7.20  feet 
at  one  end,  and  19.60  feet  at  the  other  end.  This  has  a  mean 
height  of  (one-half  the  sum  of  its  end-heights)  19.60  added  to 
7.20,  and  the  sum  divided  by  2—13.40. 

7.20 — end  height  has  a  tabular  "  end  area"  of     -  107.1 

19.60 — end  height  has  a  tabular  end'area  of    -        -        -        -    741.7 
13.40 — mean  height  has  a  tabular  "  4  times  middle  area"  of  -    1412.8 

Total,      .      -     2261.6 
Multiplied  by  length  -  13 

Cubic  yards  in  the  13  feet  prism    -    -    294.00.8 


148  PRINCIPLES   AND   PRACTICE   OF 

This  will  save  some  trouble,  as  otherwise  the  calculation  for 
the  13  feet  must  be  made  under  the  formula  in  extenso.  The 
remaining  quantities  in  the  above  form  of  measurement  are 
obtained  in  the  same  manner  as  those  of  the  foregoing  expla- 
nations. The  quantities  of  embankments  having  a  crown  of 
3  feet  across  and  a  base  of  six-fold  width,  are  to  be  calculated 
by  table  No.  2.  A  seven- fold  width  of  base  having  a  crown  of 
3  feet  wide  presents  a  section  whose  quantities  must  be  calcu- 
lated by  table  No.  3.  The  use  of  these  two  tables  is  precisely 
similar  to  that  of  table  No.  1. 

Tables  1,  2,  and  3  are  confined  in  their  application  to  new  or 
well  preserved  embankments.  Old  Levees,  however,  with 
worn  crowns,  hollowed  sides,  and  spread  bases,  cannot  be  meas- 
ured with  any  approach  to  truth  by  a  rule  based  on  a  uniform 
width  of  crown  and  constant  rate  of  base.  Estimation  under 
such  circumstances  can  be  made  only  by  a  series  of  careful 
cross-sectioning  ;  and  in  order,  therefore,  to  meet  this  necessity 
of  the  present  works  in  Levee  management,  a  table  of  contents 
is  added  here  on  the  basis  of  sectional  areas.  Table  No.  4  aims 
at  this  object.  Irregular  works  being  the  special  subject  for 
the  use  of  this  table,  it  may  be  necessary  to  observe  that  it  is 
equally  applicable  to  works  of  uniform  sections.  The  rule  for 
using  table  No.  4  is  as  follows  :  For  lengths  of  100  feet  add 
to  the  cubic  yards  corresponding  in  the  table  to  each  of  the  given 
end  areas,  4  times  the  cubic  yards  corresponding  to  the  mean  of 
those  two  areas,  and  the  sum  will  be  the  content  of  the  bank  in 
cubic  yards.  Or  another  rule  for  using  table  No.  4  :  Add  for 
lengths  of  WO  feet  the  two  end  areas  to  4  times  the  mean  of  those 
two  end  areas,  and  the  number  corresponding  in  the  table  to  the 
total  of  these  is  the  content  of  the  bank  in  cubic  yards.  For 
shorter  lengths  than  100  feet,  multiply  the  result  in  either  of 
the  above  rules  by  the  length,  and  changing  the  decimal  point 
two  figures  to  the  left,  the  product  is  the  content  in  cubic  yards. 
The  sectional  areas  in  the  tables  are  given,  it  may  be  observed, 


EMBANKING  LANDS   FROM  RIVER-FLOODS. 


149 


in  square  feet.  Taking  a  few  of  the  prismoids  in  the  form  of 
measurement-book  already  given,  the  sectional  areas  are  as 
follows,  as  estimated  by  table  No.  4  : 

Form  of  Measurement- Book  for  Table  No.  IV. 


WIDTHS. 

• 

Sectional 

Contents  in 

Strikes. 

Height. 

Crown. 

Base. 

Average 
widths. 

Areas. 

Mean  Area. 

Cubic  Yards. 

0 

5.00 

5 

80.00 

IT.  50 

8T.50 

90.81 

i 

5.20 

5 

81.20 

^18.10 

94.12 

836.8 

104.  TT 

2 

5.80 

5 

84.80 

19.90 

115.42 

888.0 

106.  4T 

3 

5.30 

5 

81.80 

18.40 

9T.52 

894.0 

104.62 

4 

5.  TO 

5 

34.20 

19.60 

111.T2 

88T.4 

1 

First  prismoid — less  end  area  87.50 

greater  end  area  94.12 

4  times  middle  area  363.24 

Total  544.86 

The  solid  content  corresponding  in  table  No.  4  to  this  aggre- 
gate "  area"  544.86  is  336.4  cubic  yards. 

Second  prismoid — less  end  area — 94.12 

greater  end  area — 115.42 

4  times  mean  area — 419.08 


Total 


628.62 


Running  the  eye  down  the  column  "  areas  in  square  feet "  of 
table  No.  4,  it  rests  on  the  large  figures  620  ;  and  following 
down  the  column  to  the  single  figure  8,  the  number  corres- 
ponding to  628  is  seen  to  be  387.6.  By  the  aid  of  the  auxil- 
iary table  subjoined  to  table  4  the  proportional  value  in  cubic 
yards  corresponding  to  the  decimal  of  the  areas,  .62  is  to  be 
added  to  the  solid  content  of  the  whole  numbers.  The  cubic 
yards  corresponding  to  the  aggregate  area  of  628.62  shows, 
therefore,  a  solid  content  of  388.0  cubic  yards.  This  explanation 
is  sufficient  to  make  the  use  of  table  No.  4  perfectly  clear.  For 


150  PRINCIPLES   AND   PRACTICE   OF 

the  particular  measurements  contemplated  by  this  table  it  will 
be  found  a  most  valuable  assistant  to  the  calculator  who  aims 
at  close  and  careful  calculation. 

All  the  tables  in  this  book  are  new  to  the  profession  ;  tables 
1,  2,  and  3,  being  modifications  from  the  practice  of  Mr.  M.  Butt 
Hewson  ;  table  No.  4  being,  however,  purely  original.  Tables 
Nos.  1,  2  and  3,  respectively,  condense  in  a  small  sheet  con- 
taining 60  lines  and  16  columns,  a  number  of  results  in  cubic 
yards  that  cannot,  in  the  ordinary  diagonal  tables  of  earth- works, 
be  given  in  a  smaller  space  than  that  occupied  by  480  lines  and 
480  columns.  Earth-work  tables  in  general,  limit  their  facilities 
to  heights  of  full  feet ;  and  therefore,  tables  1,  2,  and  3,  an- 
nexed to  this,  w7hile  much  more  condensed  in  form  and  much 
more  facile  of  reference,  make  a  great  advance  in  going  into 
detail  so  minute  as  that  involved  in  heights  of  feet  and  tenths 
of  a  foot.  It  is  perhaps  unnecessary  to  state  that  all  these  tables 
are  equally  applicable  to  cut  and  to  bank,  whether  on  Levee, 
Canal  or  Railroad. 

In  conclusion  it  may  be  added  that  these  remarks,  whether 
in  theory  or  in  practice,  have  been  of  necessity  generalities. 
Engineering  on  Levees  is  in  the  crude  state  of  those  improve- 
ments, work  for  a  man  of  some  original  observation,  some 
original  resources,  some  scientific  and  practical  skill.  Correct 
measurement  will  be  brought  by  the  remarks  made  above 
within  the  compass  of  men  of  intelligence  under  ordinary 
circumstances  •  but  the  special  circumstances  for  even  separa- 
ting Levee-practice  from  general  rules — spreading  of  base, 
sinkings  of  foundations,  bulgings  of  sides,  inundating  of  work- 
pits,  &c. — make  it  necessary  for  proper  estimation  of  those 
works  that  they  be  always  placed  in  the  charge  of  some  on  e 
thoroughly  conversant  with  the  elementary  principles  of  meas- 
urement. Location  alone  involves  so  many  delicate  and  intri- 
cate considerations — these  again  involving  so  many  serious  if 
not  fatal  contingencies — as  to  require,  superior  to  all  rules  of 


. 
EMBANKING  LANDS  FROM  RIVER-FLOODS.  151 

practice  the  eye  and  mind  of  a  professional  Engineer.  The 
detail  surveys  suggested  above  are  undertakings,  too,  that  in 
the  hands  of  even  a  decent  pretender  to  professional  ability  will 
result  in  a  simple  waste  of  money.  The  Trigonometrical 
survey  for  connecting  the  Levees  on  both  sides  of  the  River  is 
a  duty  from  which  (let  unfitness  be  ever  so  ready  to  undertake 
it)  even  the  regular  Engineer,  who  has  never  directed  his 
mind  or  his  practice  to  such  a  system  of  survey,  will  be  found 
in  honor  and  self-consciousness  to  decline.  Finally  :  if  any- 
thing that  has  been  said  here  shall  further  the  interests  of 
Levees,  shall  bring  those  works  more  thoroughly  within  the 
rules  of  art,  shall  strengthen  the  hands  of  the  administrator 
entrusted  with  their  charge,  or  shall  correct  errors  of  opinion 
on  the  part  of  planters  and  others  hampering  the  intelligence 
of  his  aims,  the  writer  shall  have  felt  rewarded  with  the  satis- 
faction of  having  left  the  impress  of  his  experience  in  the 
great  Yalley  after  him  as  a  souvenir  for  the  benefit,  in  a  greater 
or  less  degree,  of  the  very  highest  interests  of  a  generous 
people,  amongst  whom  he  has  spent  many  a  happy  day  of  work 
and  pleasure. 


THE    END. 


TABLES 
Nos.  1,  2,  3,  and  4. 


154 


PRINCIPLES   AND  PRACTICE   OF 


TABLE  I. 

Table  of  cubic  yards  corresponding  to  a  cross  section 


Decimals  of 
a  foot. 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

Decimals  of 
afoot. 

1 

foot. 

2 

feet. 

3 

feet. 

4 

feet. 

.00 

8.4 

13.6 

10.5 

42.0 

21.2 

84.8 

35.8 

143.2 

.OO 

.05 

8.7 

14.7 

10.9 

43.8 

21.9 

87.6 

866 

146.5 

.05 

.10 

8.9 

15.8 

11.4 

45.6 

22.6 

90.3 

37.5 

149.8 

.10 

.15 

4.2 

16.9 

11.9 

47.6 

23.2 

93.0 

883 

153.3 

.15 

.20 

4.5 

18.1 

12.4 

49.4 

23.9 

95.6 

89.2 

156.6 

.20 

.25 

4.8 

19.4 

12.8 

51.4 

24.6 

98.3 

40.1 

160.6 

.25 

.30 

5.2 

20.7 

13.4 

53.4 

253 

101.0 

40.9 

163.5 

.30 

.85 

5.5 

21.9 

13.8 

55.4 

25.9 

103.8 

41.7 

167.0 

.85 

.40 

5.8 

23.2 

14.4 

57.5 

26.7 

106.6 

42.6 

170.6 

.40 

.45 

6.1 

24.5 

14.9 

59.6 

27.4 

109.5 

43.5 

174.2 

.45 

.50 

6.5 

25.9 

15.4 

61.7 

28.1 

112.4 

44.4 

177.8 

.50 

.55 

6.8 

27.8 

16.0 

63.9 

28.9 

115.5 

45.3 

181.4 

.55 

.60 

7.2 

28.8 

16.5 

66-1 

29.6 

118.2 

463 

185.1 

.60 

.65 

7.6 

30.8 

17.1 

68-4 

80.3 

121.2 

472 

188.9 

.65 

.70 

8.0 

81.9 

17.7 

70-6 

81.1 

1242 

48.2 

192.6 

,7O 

.75 

8.4 

as.5 

18.2 

73.0 

31.8 

127.3 

49.1 

196.5 

.75 

.80 

8.8 

85.1 

18.8 

75.4 

32.6 

130.4 

50.1 

200.3 

.80 

.85 

9.2 

86.8 

19.4 

77.8 

83.4 

133.6 

51.0 

204.2 

.85 

.90 

9.7 

8S.5 

20.1 

80.2 

842 

136.7 

52.0 

208.2 

.90 

.95 

10.0 

40.2 

20.6 

82.5 

35.0 

140.0 

53.0 

212.1 

.95 

5 

feet. 

6 

feet. 

7 

feet. 

8 

feet 

.OO 

54.0 

216.1 

75.9 

803.7 

101.5 

406.2 

130.9 

523.5 

.OO 

.05 

55.0 

220.1 

77.1 

808.5 

102.9 

411.7 

132.4 

529.7 

.05 

.10 

56.0 

224.2 

78.8 

813.3 

104.3 

417.3 

184.0 

536.0 

.10 

.15 

57.0 

228.2 

79.5 

318.1 

105.7 

422.8 

1.35.6 

542.3 

.15 

.20 

58.1 

232.4 

80.8 

823.0 

107.1 

428.4 

137.2 

548.7 

.20 

.25 

59.1 

236.6 

82.0 

327.9 

108.5 

434.1 

138.8 

555.1 

.25 

.30 

60.2 

240.8 

83.2 

332.9 

110.0 

439.8 

140.4 

561.5 

.30 

.85 

61.2 

245.0 

84.5 

337.9 

111.4 

445.5 

142.0 

568.0 

.35 

.40 

62.8 

249.3 

85.7 

342.9 

112.8 

451.3 

143.6 

574.5 

.40 

.45 

63.4 

258.7 

87.0 

848.0 

114.3 

457.1 

145.3 

581.1 

.45 

.50 

64.5 

258.0 

88.8 

353.1 

115.7 

463.0 

146.9 

587.7 

.50 

.55 

65.6 

262.4 

89.5 

858.2 

117.2 

468.8 

148.6 

594.3 

.55 

.60 

66.7 

266.9 

90.9 

363.4 

118.7 

474.8 

150.2 

600.9 

.60 

.65 

67.8 

271.4 

92.1 

808.  6 

120.2 

480.7 

151.9 

607.6 

.65 

.70 

69.0 

275.9 

93.5 

3739 

121.7 

486.7 

153.6 

614.4 

.70 

.75 

70.1 

280.4 

94.8 

379.2 

123.2 

492.7 

155.3 

621.1 

.75 

.80 

71.8 

285.0 

96.1 

384.5 

124.7 

498.8 

157.0 

628.0 

.80 

.85 

72.4 

289.6 

97.5 

389.9 

126.2 

504.9 

158.7 

634.8 

.85 

.90 

73.6 

294.8 

98.8 

395.3 

127.8 

511.1 

160.4 

641.7 

.90 

.95 

74.7 

299.0 

100.2 

400.7 

129.3 

517.2   |i     162.1 

648.6 

.95 

9 

feet. 

10 

feet. 

11 

feet. 

12 

feet. 

1 

.00 

1639 

655.6 

200.6 

802.5 

241.1 

964.2 

2852 

1140.7 

.OO 

.05 

165.6 

662.6 

202.5 

810.2 

243.2 

972.7 

287.5 

1150.0 

.05 

.10 

167.4 

669.7 

204.5 

818.0 

245.8 

981.2 

2898 

1159.2 

.10 

.15 

169.2 

676.7 

206.4 

825.8 

247.4 

989.8 

292.1 

1168.5 

.15 

.20 

170.9 

6S3.8 

208.4 

883.6 

249.6 

998.3 

294.5 

1177.8 

.20 

.25 

172.7 

690.9 

210.4 

841.5 

251.7 

1006.7 

296.8 

1187.3 

.25 

.30 

174.5 

698.1 

2124 

849.4 

253.9 

1015.6 

299.2 

1196.7 

.30 

.85 

176.8 

705.8 

214.3 

857.4 

256.1 

1024.8 

801.5 

1206.1 

.85 

.40 

178.1 

712.5 

216.3 

865.4 

258.3 

1033.0 

803.9 

1215.5 

.40 

.45 

180.0 

719.9 

218.3 

873.4 

260.4 

1041.8 

806.2 

1225.0 

.45 

.50 

181.8 

727.2 

220.4 

881.5 

262.7 

1050.6 

308.6 

1284.6 

.50 

.55 

188.6 

734.5 

222.4 

889.  6 

264.9 

1059.5 

811.0 

1244.2 

.55 

.60 

185.5 

741.9 

224.4 

897.7 

267.1 

1068.4 

818.4 

1253.8 

.60 

.65 

187.3 

749.4 

226.5 

905.9 

269.3 

1077.3 

815.8 

1263.4 

.65 

.70 

189.2 

756.8 

228.5 

914.1 

271.6 

1086.2 

318.3 

1273.1 

.70 

.75 

191.1 

764.4 

230.6 

922.4 

278.8 

1095.2 

820.7 

1282.9 

.75 

.80 

193.0 

771.9 

232.7 

930.7 

276.1 

1104.2 

823.2 

1292.6 

.80 

.85 

194.9 

779.5 

234.7 

939.0 

278.3 

1113.3 

825.6 

1302.5 

.85 

.90 

196.8 

787.1 

236.8 

947.4 

280.  6 

1122.4 

328.1 

1312.3 

.90 

.95 

198.7 

794.8 

238.9        955.8 

282.9 

1131.6 

330.5 

1322.2 

.95 

• 

EMBANKING   LANDS   FEOM   EIVEE-FLOODS. 


155 


TABLE   I.— (Continued.} 
5  feet  wide  an  top  and  6  feet  wide  at  base  for  every  foot  high. 


Decimals  of 
a  foot. 

End 
areas. 

4  times 
middle 
area. 

End 

areas.  ~ 

4  times 
middle 
area: 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

Decimals  of 
a  foot. 

13 

feet. 

14 

feet. 

15 

feet. 

16 

feet. 

.00 

333.0 

1332.1 

384.6 

1533.3 

439.8 

1759.3 

498.8 

1995.1 

.00 

.05 

835.5 

1342.1 

387.2 

1549.0 

442.7 

1770.8 

501.8 

2007.2 

.05 

.10 

3380 

1352.0 

889.9 

15597 

445.5 

1782.2 

504.9 

2019.4 

.10 

.15 

3405 

13(5-2.  1 

392.6 

1570.5 

4484 

1793.7 

507.9 

2031.7 

.15 

.20 

3430 

1372.2 

395.3 

15813 

451.3 

1805.2 

511.0 

2044.0 

.20 

.25 

345.6 

1382  3 

!     398.0 

1592.2 

454.2 

1816.8 

514.1 

2056.4 

.25 

.30 

348.1 

1392.4 

400.8 

1608.0 

457.1 

1828.4 

517.2 

2068.7 

.30 

.35 

350.6 

1402.6 

403.5 

1613.9 

460.0 

1840.1 

520.3 

2081.1 

.85 

.40 

353.2 

1412.8 

406.2 

1624.9 

462.9 

1851.8 

5234 

2093.5 

,4O 

.45 

355.8 

1423.1 

4090 

1635.9 

465.9 

1863.6 

526.5 

2106.0 

.45 

.50 

358.3 

14:33  3 

411.7 

1646.9 

468.8 

1875.3 

529.6 

2118.5 

.50 

.55 

360.9 

1443.7 

414.5 

1658.0 

471.7 

1887.0 

532.7 

2131.0 

.65 

.60 

3635 

1454.0 

417.3 

1669.1 

474.7 

1898.7 

535.9 

2143.6 

.60 

.65 

866.0 

1464.0 

420.1 

16S0.3 

477.7 

1910.7 

539.1 

2156.3 

.65 

.70 

368.7 

1474.9 

4229 

1691.4 

480.7 

1922  8 

542.2 

2168.9 

.70 

.75 

371.3 

14S5.4 

425.6 

1702.6 

4S3.7 

1934.7 

545.4 

2181.7 

.75 

.SO 

374.0 

1495.8 

428.5 

1713.9 

486.7 

1946.6 

548.6 

2194.4 

.80 

.85 

376.6 

1506.4 

431.3 

1725.2 

489.7 

1958.7 

551.7 

2207.0 

.85 

.90 

379.3 

1517.0 

434.1 

1735.6 

492.7 

1970.8 

554.9 

2219.6 

.90 

.95 

381.9 

1527.6 

436.9 

1747.8 

495.7 

1982.9 

558.1 

2232.6 

.95 

17 

feet. 

18 

feet. 

19 

feet. 

20 

feet. 

.00 

561.4 

2245.7 

6278 

2511.1 

697.8 

2791.4 

7716 

3086.4 

.OO 

.05 

564.6 

2258.6 

6312 

2524.8 

701.4 

2805.8 

775.4 

3101.6 

.05 

.10 

567.9 

2271.6 

634.6 

2538.5 

705.1 

2820.2 

779.2 

8116.7 

.10 

.15 

571.1 

22846 

638.0 

2552.2 

708.7 

2884.7 

783.0 

8131.9 

.15 

.20 

574.4 

2297.6 

641.5 

2566.0 

712.8 

2849.2 

786.8 

3147.2 

.20 

.25 

577.7 

2310.7 

644.9 

2579.8 

715.9 

2863.7 

790.6 

8162.5 

.25 

.30 

580.9 

2323.8 

648.4 

2593.6 

719.6 

2878.3 

794.5 

31779 

.30 

.35 

584.2 

2336.9 

651.9 

2607.5 

723.2 

2898.0 

798.3 

8193.2 

.35 

.40 

587.5 

2350.1 

655.4 

2621.4 

726.9 

2907.6 

802.2 

8208.6 

.40 

.45 

590.8 

2363.3 

6588 

2635.4 

780.6 

29223 

806.0 

3224.0 

.45 

.50 

594.1 

2376.6 

662.3 

2649.4 

734.3 

2937.0 

8099 

82395 

.SO 

.55 

597.5 

2389.9 

665.9 

2663.5 

737.9 

2951.8 

813.8 

3255.1 

.55 

.60 

600.8 

2403.2 

669.4 

2677.5 

741.7 

2966.6 

817.6 

8270.6 

.60 

.65 

604.1 

24166 

672.9 

2691.6 

745.4 

2981.5 

821.5 

3286.2 

.65 

.70 

607.5 

2429.9 

676.4 

2705.7 

749.1 

2996.3 

825.4 

8301.8 

.70 

.75 

610.8 

2443.3 

680.0 

2719.9 

752.8 

3011.2 

829.4 

8317.5 

.75 

.80 

614.2 

2-156.8 

683  5 

2784.1 

756.6 

80262 

833.3 

88331 

.SO 

.85 

6176 

2470.3 

687.1 

2748.4 

760.3 

8041.1 

837.2 

3848.9 

.85 

.90 

621.0 

2483.9 

690.7 

2762.7 

764.1 

3056.2 

841.2 

8364.6 

.90 

.95 

624.4 

2497.5 

694.2 

2777.0 

767.8 

3071.3 

845.1 

33S0.4 

.95 

21 

feet. 

22 

feet. 

23 

feet. 

24 

feet. 

.OO          1    849.1 

3396.4 

930.2 

3721.0 

10151 

4060.5 

1103.7 

4414.8 

.OO 

.05 

853.0 

34122 

934.4 

3737.7 

1019.5 

4077.9 

1108.2 

4482.9 

.05 

.10 

857.0 

8428.1 

938.6 

3754.3 

1023.8 

4095.3 

1112.8 

4451.1 

.10 

.15 

861.0 

8444.0 

942.7 

3771.0 

1028.2 

4112.7 

1117.3 

4469.3 

.15 

.20 

865.0 

3460.0 

946.9 

3787.7 

1032.5 

4130.2 

1121.9 

4487.5 

.20 

.25 

869.0 

34761 

951.1 

3804.5 

1036.9 

4147.7 

1126.4 

4505.8 

25 

.30 

873.0 

3492.2 

955.3 

3821.3 

1041.8 

4165.2 

1131.0 

4524.0 

,3O 

.85 

877.1 

85083 

959.5 

3838.1 

1045.7 

4182.8 

1135.6 

4542.3 

.85 

.40 

|  881.1 

3524.4 

963.8 

8855.0 

1050.1 

4200.4 

11402 

4560.7 

.40 

.45 

885.1 

8540.6 

9680 

3872.0 

1054.5 

4218.1 

11448 

4579.1 

.45 

.50 

889.2 

3556.8 

972.2 

8888.9 

1059.0 

4235.8 

1149.4 

4597.5 

.50 

.55 

893.2 

3573.0 

976.5 

3905.9 

1063.4 

4253.6        1154.0 

4616.0 

.55 

.60 

897.3 

35S9.3 

980.7 

8922.9 

1067.8 

4271.3 

1158  6 

4634.5 

.60 

.65  i 

901.2 

8605.7 

9850 

3910.0 

1072.3 

4289.1 

1163.3 

4653.1 

.65 

.70 

905.5 

8622.1 

989.3 

3957.1 

1076.7 

4306.9 

1167.9 

4671.7 

.70 

.75 

909.6 

3638.5 

993.6 

8974.3 

10812 

4324.8 

1172.6 

4690.3 

.75 

.80 

913.7 

3654.9 

1     997.9 

3991.4 

1085.7 

4342.7 

1177.2 

4708.9 

.SO 

.85 

917.8 

3671.4 

1002.1 

4008.6 

1090.2 

4360.7 

1181.9 

4727.7 

.85 

.90 

922.0 

8687.9 

1006.5 

4025.9 

10947 

4378.7 

1186.6 

4746.4 

.90 

.95 

926.1 

3704.4 

1010.8 

4043.2 

1099.2 

4396.8 

11913 

4765.1 

.95 

156 


PRINCIPLES   AND   PRACTICE   OF 


TABLE   IL 

Table  of  Cubic  Yards  corresponding  to  a  cross  section  3  feet  wide 


Decimals 
of  a  foot. 

End 

areas. 

4  times 
middle 

End 
areas. 

4  times 
middle 

End 
areas. 

4  times 
middle 

End 
areas. 

4  times 
middle 

Decimals 
of  a  foot. 

area. 

area. 

area. 

area. 

1 

foot. 

2 

feet. 

3 

feet. 

4 

feet. 

.00 

2.8 

11.1 

9.3 

87.0 

19.4 

77.8 

88.3 

133.8 

.00 

.05 

8.0 

12.1 

9.7 

88.7 

20.1 

80.3 

84.1 

136.5 

.05 

.10 

8.3 

13.0 

10.1 

40.4 

20.7 

82.7 

84.9 

139.7 

.to 

.15 

8.5 

14.0 

10.5 

42.2 

21.3 

85.2 

85.7 

142.9 

.15 

.20 

8.8 

15.1 

11.0 

44.0 

21.9 

87.7 

86.6 

146.2 

.20 

.25 

4.0 

16.2 

11.4 

45.8 

22.7 

90.8 

37.3 

1493 

.25 

.30 

4.8 

17.3 

11.9 

47.7 

23.2 

93.8 

88.2 

152.9 

.30 

.85 

4.6 

18.5 

12.4 

49.7 

24.0 

96.0 

39.1 

156.3 

.85 

.40 

4.9 

19.7 

12.9 

51.6 

24.6 

98.2 

39.9 

159.7 

.40 

.45 

5.2 

21.0 

13.4 

53.5 

25.2 

100.9 

40.8 

163.2 

.45 

.50 

6.6 

22.2 

13.9 

55.5 

25.9 

103.7 

41.7 

166.7 

.50 

.55 

5.9 

23.5 

14.4 

57.6 

26.6 

106.5 

42.6 

170.3 

.55 

.60 

62 

24.9 

14.9 

59.7 

27.3 

109.3 

43.4 

1738 

.60 

.65 

6.6 

26.8 

15.4 

61.8 

28.0 

112.2 

44.3 

177.4 

.65 

.70 

6.9 

27.7 

16.0 

64.0 

2S.8 

115.1 

45.3 

181.0 

.70 

.75 

7.8 

29.2 

16.5 

66.2 

29.5 

118.0 

46.2 

1S4.9 

.75 

.80 

7.7 

80.7 

17.1 

6S.4 

80.3 

121.0 

47.1 

188.4 

.80 

.85 

8.1 

82.3 

17.7 

70.7 

31.0 

124.1 

48.0 

192.2 

.85 

.90 

8.4 

33.8 

18.3 

73.0 

81.8 

127.1 

49.0 

196.0 

.90 

.95 

8.8 

85.4 

18.8 

75.4 

82.5 

.   130.2 

50.0 

199.9 

.95 

5 

feet. 

6 

feet. 

7 

feet 

8 

feet. 

.00 

50.9 

203.7 

72.2 

288.9 

97.2 

388.9 

125.9 

503.7 

.00 

.05 

51.9 

207.6 

73.4 

293.6 

98.6 

894.3 

127.5 

509.9 

.05 

.10 

52.9 

2)1.6 

74.6 

298.2 

99.9 

899.7 

129.0 

516.0 

.10 

.15 

53.9 

215.6 

75.7 

803.0 

101.8 

405.2 

130.5 

522.2 

.15 

.20 

54.9 

219.6 

76.9 

807.7 

102.7 

410.7 

132.1 

5284 

.20 

.25 

55.9 

223.6 

78.1 

312.5 

104.1 

416.3 

133.7 

534.7 

.25 

.30 

56.9 

227.7 

79.3 

817.3 

105.4 

421.8 

135.3 

541.0 

.30 

.85 

53.0 

281.9 

80.5 

822.2 

106.8 

427.4 

K6.8 

547.4 

.35 

.40 

59.0 

236.0 

81.8 

827.1 

108.8 

433.0 

138.4 

553.8 

.40 

.45 

60.0 

240.2 

83.0 

832.0 

109.7 

438.7 

140.1 

560.8 

.45 

.50 

61.1 

244.4 

84.8 

837.0 

111.1 

444.4 

141.7 

566.7 

.50 

.55 

62.2 

248.7 

85.5 

342.1 

112.5 

450.2 

143.3 

573.2 

.55 

.60 

63.8 

253.0 

86.8 

847.1 

114.0 

456.0 

144.9 

579.7 

.60 

.65 

64.3 

257.4 

88.0 

352.2 

115.4 

461.8 

146.6 

586.3 

.65 

.70 

65.4 

261.8 

89.3 

357.3 

116.9 

467.7 

148.2 

592.9 

.70 

.75 

66.6 

266.3 

90.6 

862.5 

118.4 

473.7 

149.9 

599.6 

.75 

.80 

67.7 

270.7 

91.9 

867.7 

119.9 

479.6 

151.6 

606.3 

.80 

.85 

68.8 

275.4 

93.2 

873.0 

121.4 

485.6 

153.2 

613.0 

.85 

.90 

69.9 

279.7 

94.6 

878.2 

122.9 

491.6 

154.9 

619.7 

.90 

.95 

71.1 

284.3 

95.9 

883.6 

124.4 

497.7 

156.6 

626.5 

.95 

9 

feet 

10 

feet 

11 

feet. 

12 

feet 

.00 

158.8 

6338 

194.4 

777.8 

234.3 

937.0 

277.8 

lill.l 

.00 

.05 

160.0 

640.2 

196.3 

785.4 

236.3 

945.4 

280.5 

1122.2 

.05 

.10 

161.8 

647.1 

198.3 

793.0 

23S.4 

953.8 

2S2.8 

1129.3 

.10 

.15 

163.5 

654.0 

200.2 

800.7 

240.6 

962.3 

2S4.6 

1188.5 

.15 

.20 

165.3 

661.0 

202.1 

808.4 

242.7 

970.7 

286.9 

1147.7 

.20 

.25 

167.0 

668.1 

204.1 

816.4 

244.8 

979.2 

2S9.2 

1156.9 

.25 

.30 

168.8 

675.1 

206.0 

824.0 

246.9 

9S7.7 

291.6 

1166.2 

.30 

.85 

170.5 

682.2 

207.9 

831.8 

249.1 

996.3 

293.9 

1175.6 

.35 

.40 

172.3 

689.8 

209.9 

839.7 

251.2 

1004.9 

296.2 

1184.9 

.40 

.45 

174.1 

696.5 

211.9 

847.7 

253.4 

1013.6 

298.6 

1194.3 

.45 

.50 

175.9 

703.7 

213.9 

855.6 

255.6 

1022.2 

800.9 

1203.7 

.50 

.55 

177.7 

711.0 

215.9 

863.6 

257.7 

1030.9 

303.8 

1213.2 

.55 

.60 

179.6 

718.2 

217.9 

871.6 

259.9 

1039.7 

805.7 

1222.7 

.60 

.65 

181.4 

725.6 

219.9 

879.7 

262.1 

1048.5 

808.1 

1232.8 

.65 

.70 

183.2 

732.9 

221.9 

887.7 

264.8 

1057.3 

810.5 

1242.0 

.70 

.75 

185.1 

740.3 

224.0 

895.9 

266.5 

1066.2 

812.5 

1251.5 

.75 

.SO 

186.9 

747.7 

226.0 

904.0 

268.8 

1075.1 

815.3 

1261.0 

.80 

.85 

188.8 

755.2 

228.0 

912.2 

271.0 

1084.0 

817.6 

1270.6 

.85 

.90 

190.7 

762.7 

230.1 

920.4 

273.3 

1093.0 

820.1 

1280.2 

.90 

.95 

192.6 

770.3 

232.2 

928.7 

275.5 

1102.0 

322.5 

1290.1 

.95 

EMBANKING   LANDS  FKOM  RIVEB-FLOODS. 


157 


TABLE   H.— (Continued.) 
on  top  and  6  feet  wide  at  base  for  every  foot  high. 


Decimals  of 
a  foot. 

End 

areas. 

4  times 
middle 
area. 

1 
End 
areas. 

4  times 
,  middle 
area. 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

Decimals  of 
a  foot. 

13 

feet. 

14 

feet. 

15 

feet. 

~"l6 

feet. 

.00 

825.0 

1300.0 

875.9 

1503.7 

430.6 

1722.2 

488.9 

1955.6 

.OO 

.05 

827.0 

1809.9 

878.6 

1514.8 

438.4 

1788.6 

491.9 

1967.7 

.05 

.10 

329.9 

1319.7 

381.2 

1524.9 

436.2 

1744.9 

494.9 

1979.7 

.10 

.15 

332.4 

1829.7 

383.9 

1535.6 

489.1 

1756.8 

498.0 

1991.9 

.15 

.20 

334.9 

1339.6 

386.6 

1546.2 

441.9 

1767.7 

501.0 

2004.0 

.20 

.25 

837.4 

1349.6 

889.2 

1556.9 

444.8 

1779.2 

504.0 

2016.2 

.25 

.30 

839.9 

1:359.6 

391.9 

1567.7 

447.7 

1790.7 

507.1 

2028.4 

.30 

.35 

842.4 

1369.7 

394.6 

1578.5 

450.5 

1802.2 

510.2 

2040.7 

1.85 

.40 

344.9 

1879.7 

1     897.3 

1589.8 

453.4 

1818.8 

513.8 

2053.0 

.40 

.45 

847.5 

13S9.9 

1     400.0 

1600.2 

456.3 

1825.4 

516.8 

2065.4 

.45 

.50 

3500 

1400.0 

402.8 

1611.1 

459.3 

1837.0 

519.4 

2077.8 

.50 

.55 

352.5 

1410.2 

405.5 

1622.1 

462.2 

1848.7 

522.6 

2090.3 

'.55 

.60 

355.1 

1420.4 

40S.3 

1633.0 

465.1 

1860.4 

1     525.7 

2102.7 

.60 

.65 

857.7 

1430.7 

411.0 

1644.1 

468.0 

1872.2 

528.8 

2115.2 

.65 

.70 

3603 

1441.0 

413.8 

1655.1 

471.0 

1884.0 

531.9 

2127.7 

.70 

.75 

362.8 

1451.4 

416.5 

1666.2 

473.9 

1895.8 

535.1 

2140.8 

.75 

.80 

365.4 

1461.8 

419.3 

1677.3 

476.9 

1907.7 

538.2 

2152.9 

.80 

.85 

868.1 

1472.3 

422.1 

1688.5 

479.9 

1919.7 

541.4 

2165.6 

.85 

.90 

370.7 

1482.7 

424.9 

1699.7 

482.9 

1931.6 

544.6 

2178.2 

.90 

.95 

373.3 

1493.2 

427.7 

1711.0 

485.9 

1943.6 

547.7 

2191.0 

.95 

17 

feet. 

18 

feet. 

19 

feet. 

20 

feet, 

.00 

550.9 

2203.7 

616.7 

2466.7 

6S6.1 

2744.4 

759.8 

3037.0 

.OO 

.05 

554.1 

2216.5 

620.1 

2480.3 

689.7 

2758.7 

763.0 

8052.0 

.05 

.10 

557.3 

2229.3 

623.4 

2493.8 

693.3 

2773.0 

766.7 

8067.0 

.10 

.15 

560.5 

2242.2 

626.8 

2507.4 

696.8 

2787.4 

770.5 

3082.2 

.15 

.20 

563.8 

2255.1 

630.3 

2521.0 

700.4 

2801.8 

774.8 

3097.3 

.20 

.25 

5670 

2268.1 

633.7 

2534.7 

704.1 

2816.3 

778.1 

3112.5 

.25 

.30 

570.3 

2281.0 

637.1 

2548.4 

707.7 

2830.7 

781.9 

8127.7 

.30 

.85 

573.5 

2294.0  ' 

640.5 

2562.2 

711.3 

2845.2 

785.7 

8143.0 

.85 

.40 

5768 

2307.1 

644.0 

2576.0 

714.9 

2859.7 

789.6 

3158.2 

.40 

.45 

580.0 

2320.2 

647.4 

2589.8 

718.6 

2874.3 

798.4 

81786 

.45 

.50 

583.8 

2333  3 

650.9 

2603.7 

7222 

2888.9 

797.2 

3188.9 

.50 

.55 

586.6 

2346.5 

654.4 

2617.7 

725.9 

2903.6 

801.8 

8204.3 

.55 

.60 

589.9 

2359.7 

657.9 

2631.6 

729.6 

2918.2 

804.9 

8219.7 

.60 

.65 

593.2 

2373.0 

661.4 

2645.6 

733.2 

2933.0 

808.8 

3235.2 

.65 

•  7O 

596.6 

2386.2 

664.9 

2659.6 

736.9 

2947.0 

812.7 

8250.7 

.70 

.75 

5999 

2399.6 

668.4 

2673.6 

740.6 

2962.5 

816.6 

3266.3 

.75 

.80 

603.2 

2412.9 

671.9 

2687.7 

744.3 

2977.3 

820.4 

8281.8  . 

.80 

.85 

6066 

2426.3 

675.4 

2701.8 

748.0 

2992.2 

824.3 

3297.4 

.85 

.90 

609.9 

2439.7 

679.0 

2716.0 

751.8 

3007.1 

828.3 

3313.0 

.90 

.95| 

613.3 

2453.2 

682:5 

2730.2 

755.0 

3022.1 

832.2 

3328.7 

.95 

21 

feet. 

22 

feet. 

23 

feet. 

24 

feet. 

.00 

836.1 

3344.4 

916.7 

3666.7 

1000.9 

4003.7 

1088.9 

4355.6 

.OO 

.05 

840.0 

8360.2 

920.8 

3683.2 

1005.2 

4021.0 

1093.4 

4873.6 

.05 

.10 

844.0 

3376.0 

924.9 

3699.7 

1009.6 

4038.2 

1097.9 

4391.1 

.10 

.15 

848.0 

3391.9 

929.1 

3716.3 

1013.9 

4055.6 

1102.4 

44097 

.15 

.20 

851.9 

3407.7 

933.2 

8732.9 

1018.2 

4072.9 

1106.9 

4427.7 

.20 

.25 

855.9 

3423.6 

937.4 

3749.6 

1022.6 

4090.3 

1111.5 

4445.9 

.25 

.30 

859.9 

3439.6 

941.6 

3766.2 

1026.9 

4107.7 

1116.0 

4464.0 

.30 

.85 

863.9 

3455.6 

945.7 

3783.0 

1031.3 

4125.2 

1120.5 

4482.2 

.35 

.40 

867.9 

3471.6 

949.9 

3799.7 

1035.7 

4142.7 

1125.1 

4500.4 

.40 

.45 

871.9 

8487.6 

954.1 

3S16.5 

1040.1 

4160.3 

1129.7 

4518.7 

.45 

.50 

875.9 

3503.7 

958.3 

8833.3 

1044.4 

4177.8 

1134.3 

4537.0 

.50 

.55 

879.9 

3519.8 

962.5 

3850.2 

1048.8 

4195.4 

1138.8 

4555.4 

.55 

.60 

884.0 

3536.0 

966.8 

3S6T.1 

1053.3 

4213.0 

1143.4 

4573.8 

.60 

.65 

888.0 

3552.2 

971.0 

3884.1 

1057.7 

4230.7 

1148.1 

4592.3 

.65 

.70 

892.1 

8568.4 

975.3 

3901.1 

1062.1 

4248.4 

1152.7 

4610.9 

.70 

.75 

896.2 

3584.7 

979.5 

8918.1 

1066.5 

4266.2 

1157.3 

4629.3 

.75 

.80 

900.3 

3601.0 

983.8 

3935.1 

1071.0 

4284.0 

1161.9 

4647.7 

.80 

.85 

904.3 

3617.4 

9880 

3952.2 

1075.4 

4301.8 

1166.6 

4666.3 

.85 

.90 

908.4 

8633.8 

992.3 

3969.3 

1079.9 

4319.7 

1171.2 

4684.9 

.90 

.95 

912.6 

3650.3 

996.6 

3986.5 

1084.4 

4337.7 

1175.9 

4703.6 

.95 

158 


PEINCIPLES   AND   PEACTICE  OF 


TABLE   in. 

Table  of  cubic  yards  corresponding  to  a  cross  section  3  feet  wide 


Decimals 
of  a  foot. 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

End 
areas. 

4  times 
middle 
area. 

Decimals  of 
a  foot. 

1 

foot 

2 

feet. 

3 

feet. 

4 

feet. 

.00 

8.1 

12.4 

10.5 

42.0 

22.2 

88.9 

38.3 

153.1 

.00 

.05 

3.4 

13.5 

11.0 

44.0 

22.9 

91.7- 

39.2 

156.8 

.05 

.10 

3.6 

14.5 

11.5 

45.9 

23.6 

94.5 

40.1 

160.5 

.10 

.15 

3.9 

15.7 

12.0 

48.0 

24.4 

97.5 

41.1 

164.3 

.15 

.20 

4.2 

16.9 

12.5 

50.0 

25.1 

100.4 

42.0 

16S.O 

.20 

.25 

4.5 

13.2 

13.0 

52.1 

258 

103.3 

42.9 

171.8 

.25 

.30 

4.9 

19.4 

13.6 

54.2 

26.6 

106.3 

43.9 

175.7 

.30 

.35 

5.2 

20.8 

141 

56.5  ! 

27.3 

109.4 

44.9 

179.7 

.35 

.40 

5.5 

22.1 

14.7 

58.7  i 

28.1 

112.5 

45.9 

183.6 

.40 

.45 

5.9 

23.6 

15.2 

61.0 

28.9 

115.7 

46.9 

187.7 

.45 

.50 

63 

25.0 

15.8 

63.3 

29.7 

118.8 

47.9 

191.7 

.50 

.55- 

66 

26.6 

16.4 

65.7 

80.5 

122.0 

48.9 

195.8 

.55 

.60 

T.O 

28.1 

17.0 

68.1 

31.3 

125-3 

50.0 

199.9 

.60 

.65 

T.4 

29.7 

17.6 

70.6 

32.1 

128-6 

51.0 

204.1 

.65 

.TO 

7.8 

31.3 

1S.3 

73.0 

33.0 

132.0 

52.1 

208.3 

.TO 

.75 

8.2 

33.0 

18.9 

75.6 

33.9 

135.5 

53.1 

212.6 

.75 

.80 

8.T 

34.7 

19.5 

78.  1 

34.7 

13S.9 

54.2 

216.9 

.80 

.85 

i      9.1 

36.5 

20.2 

80.8 

35.6 

142.4  j 

55.3 

221.3 

.85 

.90 

9.6 

3S.3 

20.9 

as.4 

86.5 

145.9 

56.4 

225.6 

.90 

.95 

10.0 

40.2 

21.5 

86.2  ||       37.4 

149.5 

57.5 

230.1 

.95 

5 

feet. 

6 

feet. 

7 

feet. 

8 

feet. 

.00 

53.6 

234.6 

83.3 

333.3 

112.3 

449.4 

145.7 

5S2.7 

.00 

.05 

59.8 

239.2            84.7 

338.8 

113.9 

455.7 

147.4 

589.8 

.05 

.10 

609 

243.7  i         86.0 

344.2 

115.5 

461.9  ji     149.3 

597.0 

.10 

.15 

62.1 

248.3  i         87.4 

3497 

117.1 

468.3 

151.1 

604.3 

.15 

.20 

63.2 

252.9 

88.8 

355.2 

118.7 

474.7 

15-'.9 

611.5 

.20 

.25 

64.4 

257.7 

90.2 

360.8 

120.3 

481.2 

154.7 

618.8 

.25 

.30 

65.6 

262.4           91.6 

366.3 

121.9 

487.6          156.5 

626.1 

.30 

.85 

66.8 

267.2 

93.0 

3*2.0 

123.5 

494.1          158.4 

633.5 

.35 

.40 

68.0 

272.0 

94.4 

377.7 

125.2 

500  6         160.2 

640.9 

.40 

.45 

69.2 

276.9 

95.9 

883.5 

126.8 

507.3 

162.1 

648.4 

.45 

.50 

70.4 

281.8 

97.3 

8S9.2 

128.5 

513.9 

164.0 

655.9 

.50 

.55 

71.7 

2S6.8 

98.7 

395.0 

130.2 

520.7 

1659 

663.5 

.55 

.60 

72.9 

291.8 

100.2 

400.9 

131.8 

527.4 

!     167.8 

671.0 

.60 

.65 

74.7 

296.8 

101.7 

406.8 

133.5 

534.2 

169.7 

678.7 

.65 

.TO 

75.5 

301.9 

103.2 

412.7 

135.2 

540.9 

171.6 

6S6.8 

.TO 

.11 

76.7 

807.0 

104.7 

418.7 

136.9 

5478 

173.5 

694.1 

.75 

.80 

78.1 

312.2 

106.2 

424.7 

138.7 

554.7 

175.5 

701.9 

.80 

.85 

79.3 

317.5 

107.7 

430.8 

140.4 

561.7 

177.4 

709.7 

.85 

.90 

80.7 

322.7 

109.3 

437.0 

142.2 

568.6 

179.4 

717.5 

.90 

.95 

82.0 

328.0 

110.8 

443.2 

143.9 

575.7 

181.3 

725.4 

.95 

9 

feet. 

10 

feet. 

11 

feet. 

12 

feet. 

.00 

183.3 

733.8 

225.3 

901.2 

271.6 

1086.4 

322.2 

1288.9 

.00 

.05 

185.3 

741.3 

227.5 

910.1 

274.0 

1096.2 

324.9 

1299.5 

.05 

.10 

I  187.3 

749.4 

229.7 

919.0 

276.5 

1105.9 

327.5 

1310.1 

.10 

.15 

189.4 

757.5 

232.0 

92S.O 

178.9 

1115.8 

330.2 

1320.8 

.15 

.20 

191.4 

765.6 

234.2 

936.9 

281.4 

1125.6 

332.9 

1331.5 

.20 

.25 

193.4 

773.7 

236.5 

945.9 

283.9 

1135.5 

335.6 

1342.3 

.25 

.30 

195.5 

781.9 

238.7 

955.0 

286.3 

1145.4 

338.3 

1353.0 

.30 

.85 
.40 

197.5 
199.6 

79u2 

798.4 

241.0 
243.3 

964.1 
973.2 

2S9.1 
2913 

1155.4 
1165.3 

340.9 
343.7 

1363.8 
1374.7 

.85 
.40 

.45 

201.7 

806.8 

245.6 

982.5 

293.8 

1175.4 

346.4 

1385.7 

.45 

.50 

203.8 

815.1 

247.9        991.7 

296.4 

1185.5 

349.2 

1396.6 

.50 

.55 

205.9 

823.6 

250.2 

1001.0 

299.0 

1195.9 

351.9 

1407.7 

.55 

.63 

208.0 

8320 

252.6 

1010.3 

301.6 

1206.3 

354.7 

1418.7 

.60 

.65 

210.0 

840.0 

254.9 

1019.7 

304.1 

1216.3 

1     357.4 

1429.8 

.65 

.TO 

212.3 

849.0 

257.3 

1029.1 

306.6 

1226.3 

360.2 

1440.9 

.TO 

.T5 

214.4 

857.7 

259.6 

1038.5 

809.2 

1236.7  I 

863.0 

1452.1 

.75 

.80 

216.6 

866.3 

262.0 

1048.0 

311.8 

1247.0 

365.8 

1463.8 

.80 

.85 

218.7 

875.0 

264.4 

1057.5 

314.3 

1257.4 

368.6 

1474.6 

.85 

.90 

220.9 

883.7 

266.8 

1067.1 

317.0 

1267.8 

371.5 

1485.9 

.90 

.95 

223.1 

892.5 

269.2 

1076.8 

319.6 

1278.8 

374.3 

1497.3 

.95 

EMBANKING-   LANDS   FROM   KIVEK-FLOODS. 


159 


TABLE  in. — (Continued.) 
on  top  and  7  feet  wide  at  base  for  every  foot  high. 


Decimals  of 

End 

4  times 
middle 

End 

4  times 
middle 

End 

4  times 
middle 

End 

4  times 
middle 

Decimals  of 

a  foot. 

areas. 

area. 

areas. 

area, 

areas. 

area. 

areas. 

area. 

a  foot. 

13 

feet. 

14 

feet. 

15 

feet. 

16 

feet. 

.00 

377.2 

1508.6 

436.4 

1745.7 

500.0 

2000.0 

568.0 

2272.1 

.OO 

.05 

8SO.O 

1520.1 

439.5 

1758.0 

503.3 

2013.2 

571.5 

2285.9 

.05 

.10 

3S2.9 

1531.6 

442.6 

1770.3 

506.6 

2026.4 

574.9 

2299.7 

.to 

.15 

3S5.8 

1543.2 

445.7 

1782.8 

509.9 

2039.7 

578.4 

2313.8 

.15 

.20 

388.7 

1554.7 

448.8 

1795.2 

513.2 

2052.9 

582.0 

2328.0 

.20 

.25 

891.6 

1566.3 

451.9 

1807.7 

516.6 

2066.3 

5856 

2342.3 

.25 

.30 

394.5 

1577.9 

455.0 

1820.2 

519.9 

2079.7 

589.2 

2356.7 

.30 

.85 

397.4 

1589.7 

458.2 

18328 

5233 

2093.2 

592.7 

2370.9 

.35 

.40 

400.3 

1601.4 

461.3 

1845.3 

526.6 

2106.6 

596.3 

2385.1 

.40 

.45 

403.3 

1613.2 

4645 

1858.0 

530.0 

'2120.1 

599.9 

2399.5 

.45 

.50 

406.3 

1625.0 

467.7 

1870.7 

533.4 

2133.6 

603.5 

2418.9 

.50 

.55 

409.2 

1636.9 

470.9 

1883.5 

5368 

2147.3 

607.1 

2428.4 

.55 

.60 

412.2 

1648.8 

474.1 

1896.3 

540.2 

2160.9 

610.7 

2442.9 

.60 

.65 

415.2 

1660.8 

477.3 

1909.1 

543.6 

2174.6 

614.4 

2457.5 

.65 

.70 

418.2 

1672.8 

480.5 

1921.9 

547.1 

2188.3 

6180 

2472.0 

.70 

.75 

421.2 

1684.8 

433.7 

1934.8 

550.5 

2202.1 

621.7 

2486.7 

.75 

.SO 

424.2 

1696.9    1 

486.9 

1947.8 

554.0 

22159 

625.3 

2501.3 

.80 

.85 

427.2 

1709.0 

490.2 

1960.8 

557.4 

2229.8 

629.0 

2516.1 

.85 

.90 

430.3 

1721.2 

493.4 

1973.8 

560.9 

2243.7 

632.7 

2530.8 

.90 

.95 

433.4 

1733.5 

496.7 

1986.9 

564.5 

22579 

636.4 

2545.7 

.95 

17 

feet. 

18 

feet. 

19 

feet. 

£0 

feet. 

.00 

640.1 

2560.5 

716.7 

2866.7 

797.5 

3190.1 

882.7 

3530.9 

.00 

.05 

643.8 

2575.4 

720.6 

2882.5 

801.7 

3206.8 

887.1 

35484 

.05 

.10 

647.6 

2590.3 

724.6 

2898.2 

805.9 

3223.4 

891.5 

35659 

.10 

.15 

651.3 

2605.3 

728.5 

2914.1 

810.0 

8240.2 

895.9 

3583.5 

.15 

.20 

655.1 

2620.3 

732.5 

2930.0 

814.2 

3256.9 

900.3 

3601.1 

.20 

.25 

658.8 

2635.4 

736.5 

2946.0 

818.4 

8273.fi 

904.7 

3618.8 

.25 

.30 

662.6 

2650.5 

740.5 

2961.9 

822.6 

3290.4 

909.1 

3636.5 

.30 

.35 

6fi6.4 

2665.7 

744.5 

2978.0 

826.9 

3307.8 

913.6 

3654.8 

.85 

.40 

670.2 

2680.9 

748.5 

2994.0 

831.1 

3324.4 

918.0 

3672.0 

.40 

.45 

674.0 

2696.2 

752.5 

3010.1 

835.3 

3341.3 

922.4 

8689.8 

.45 

.50 

677.9 

2711.4 

756.6 

8026.2 

839.6 

8358.3 

926.9 

3707.7 

.50 

.55 

681.7 

2726.8 

760.6 

3042.5 

843.8 

3375.4 

931.4 

3725.7 

.55 

.60 

685.5 

2742.1 

764.7 

3058.7 

8481 

8392.5 

935.9 

3743.6 

.60 

.65 

689.4 

2757.6 

763.7 

3075.0 

852.4 

3409.7 

940.4 

3761.7 

.65 

.70 

693.3 

2773.0 

772.8 

8091.3 

856.7 

8426.8 

9449 

37797 

.70 

.75 

697.1 

2788.6 

776.9 

3107.7 

861.0 

3444.0   1 

949.4 

3797.8 

.75 

.80 

701.0 

2804.1 

781.0 

8124.1 

865-8 

3461.3 

954.0 

3815.9 

.80 

.85 

704.9 

2819.7 

7851 

3140.6 

869.7 

3478.7 

958.5 

8834.1 

.85 

.90 

708.8 

2835.3 

789.0 

3157.0 

874.0 

3496.1 

963.1 

8852.3 

.SO 

.95 

712.7 

2851.0 

793.4 

3178.6 

878.4 

3513.5 

967.6 

8870.6 

.95 

21 

feet. 

22 

feet. 

23 

feet. 

24 

feet. 

.OO 

972.2 

3888.9 

1066.1 

4264.2 

1164.2 

4656.8 

1266.7 

5066.7 

.QO 

.05 

976.9 

3907.7 

1070.9 

4283.5 

1169.2 

4676.9 

1271.9 

5087.6 

.05 

.10 

981.4 

3925.6 

1075.7 

4302.7 

1174.3 

4697.0 

1277.2 

5108.6 

.10 

.15 

986.0 

8944.1 

1080.5 

4322.0 

1179.3 

4717.1 

1282.4 

5129.7 

.15 

.20 

990.6 

3962.6 

1085.3 

4341.3 

1184.3 

4737.4 

1287.7 

5150.7 

.20 

.25 

994.8 

3981.2 

1090.2 

4360.8 

1189.4 

4757.6 

1292.9 

5171.8 

.25 

.30 

999.9  1  3999.7 

1095.0 

4380.2 

1194.5 

4777.9 

1298.3 

5193.0 

.33 

.35 

1004.6 

4018.3 

1099.9 

4399.7 

1199.6 

4798.3 

1303.6 

5214.3 

.85 

.40 

1009.2 

4036.9 

11048 

4419.2  • 

1204.7 

4818.7 

1308.9 

5235.5 

.40 

.45 

1013.9 

4055.7 

1109.7 

4438.8 

12098 

4839.2 

1314.2 

5256.8 

.45 

.50 

1018.6 

4074.4 

1114.6 

4458.3 

1214.9 

4859.6 

1319.5 

5278.1 

.50 

.55 

1023.3 

4093.2 

1119.5 

4478.0 

1220-0 

48801 

1824.9 

5299.5 

.55 

.60 

1028.0 

4112.0 

1124.4 

4497.7 

1225.2 

4900.6 

1330.2 

5320.9 

.60 

.65 

1032.7 

4130.9 

1129.4 

4517.5 

1230.3 

4921.3 

1335.6 

5342.4 

.65 

.70 

1037.4 

4149.8 

1134.3 

4537.2 

1235.5 

4941.9 

1341.0 

5363.9 

.70 

.75 

1042.2 

4168.8    II  1139.2 

4557.0 

1240.6 

4962.6 

1346.4 

5385.5 

.75 

.80 

1046.9 

4187.8 

1144.2 

4576.9 

1245.8 

4983.3 

1351.8 

5407.0 

.80 

.85 

1051.7 

4206.8 

11492 

4596.8 

1251.0 

5004.1 

1357.1 

5428.6 

.85 

.90 

1056.5 

4225.9 

1154.2 

4616.8 

1256.2 

5024.0 

1362.6 

5450.2 

.90 

.95 

1061.2 

4245.0 

1159.2 

4636.8 

1261.4 

5045.8 

1368.0 

5472.0 

.95 

i 

160 


PRINCIPLES   AND   PRACTICE   OF 


AUXILIARY  TO  TABLE  IV. 


WHEN     THE     AREAS     CONTAIN     DECIMAL     PARTS. 


Decimal  of  Areas. 

Decimal 
Cubic  Yards 
Corresponding. 

.00 

.0 

.17 

.1 

.33 

.2 

.50 

.3 

.66 

.4      ' 

.83 

.5 

1.00 

.6 

N.B. — When  the  square  area  consists  of  a  whole  number  and  of 
decimal  parts  of  a  whole  number,  the  cubic  yards  corresponding  to  those 
decimal  parts,  as  given  in  the  subjoined  Auxiliary  Table,  are  to  be  added 
to  the  cubic  yards  corresponding  to  the  whole  number  as  set  forth  in 
Table  IV. 


EMBANKING   LANDS    FROM    lilYER-FLOODS. 


161 


TABLE   IV. 

Table  of  Cubic  Yards  corresponding  to  areas  in  square  feet. 


Areas 
in  square  feet. 

Cubic  yards 
corresponding. 

Areas 
[  in  Equate  feet. 

Cubic  yard', 
corresponding. 

•* 

Cubic  yards 
corresponding. 

A  reas 
in  square  feet. 

fcb 

11 

li 

Areas 
in  square  feet. 

Cubic  yards 
corresponding. 

<l 

Cubic  yards 
corresponding. 

1 

0.6 

5 

40.1 

9 

79.6 

3 

119.1 

7 

15S.6 

1 

198.1 

2 

1.2 

6 

40.7 

130 

80.2 

4 

119.7 

8 

159.2 

2 

198.8 

3 

1.9 

7 

41.4 

1 

80.9 

5 

120.4 

9 

159.9 

3 

199.4 

4 

2.5 

8 

42.0 

2 

81.5 

6 

121.0 

260 

160.5 

4 

200.1 

5 

3.1 

9 

42.6 

8 

82.1 

7 

121.6 

1 

161.1 

5 

2006 

6 

3.7 

70 

43.2 

4 

82.7 

8 

122.2 

2 

161.7 

6 

201.2 

7 

4.3 

1 

43.8 

5 

83.3 

9 

122.8 

3 

162.3 

7 

201.8 

8 

4.9 

2 

444 

6 

83.9 

200 

123.4 

4 

162.9 

8 

202.4 

9 

5.5 

8 

45.1 

7 

84.6 

1 

124.1 

5 

163.6 

9 

203.1 

10 

6.2 

4 

45.7 

8 

85.2 

2 

124.7 

6 

164.2 

330 

203.7 

1 

6.8 

5 

46.3 

9 

85.8 

3 

125.3 

7 

164.8 

1 

204.3 

2 

7.4 

6 

46.9 

140 

86.4 

4 

125.9 

s 

165.4 

2 

204.9 

3 

8.0 

7 

47.5 

1 

87.0 

5 

126.5 

9 

166.0 

3 

205.5 

4 

8.6 

8 

48.1 

2 

87.6 

6 

127.1 

270 

166.7 

•  4 

206.2 

5 

9.3 

9 

48.8 

S 

88.3 

7 

127.8 

1 

167.3 

5 

206.8 

6 

9.9 

80 

49.4 

4 

88.9 

8 

128.4 

2 

167.9 

6 

207.4 

7 

10.5 

1 

50.0 

5 

89.5 

9 

129.0 

8 

168.5 

7 

208.0 

8 

11.1 

2 

50.6 

6 

90.1 

21O 

129.6 

4 

169.1 

8 

208.6 

9 

11.7 

3 

51.2 

7 

90.7 

1 

130.2 

5 

169.7 

9 

2092 

20 

12.3 

4 

51.8 

8 

91.4 

2 

130.9 

6 

170.4 

340 

209.9 

1 

13.0 

5 

52.5 

9 

92.0 

3 

131.5 

7 

171.0 

1 

210.5 

2 

13.6 

6 

53.1 

ISO 

92.6 

4 

132.1 

8 

171.6 

2 

211.1 

3 

14.2 

7 

53.7 

1 

93.2 

5 

132.7 

9 

172.2 

3 

211.7 

4 

14.8 

8 

54.3 

2 

93.8 

6 

133.8 

280 

172.8 

4 

212.3 

5 

15.4 

9 

54.9 

3 

94.4 

7 

133.9 

1 

173.4 

5 

212.9 

6 

16.0 

90 

55.5 

4 

95.1 

8 

134.6 

2 

174.1 

6 

213.6 

7 

16.7 

1 

56.2 

5 

95.7 

9 

135.2 

3 

174.7 

7 

214.2 

8 

17.3 

2 

56.8 

6 

96.3 

220 

135.8 

4 

175.3 

8 

214.8 

9 

17.9 

8 

57.4 

7 

96.9 

1 

136.4 

5 

175.9 

9 

215.4 

30 

18.5 

4 

58.0 

8 

97.5 

2 

137.0 

6 

176.5 

350 

216.0 

1 

19.1 

5 

58.6 

9 

98.1 

3 

137.6 

7 

177.1 

1 

216.7 

2 

19.8 

6 

59.3 

160 

98.8 

4 

138.3 

8 

177.8 

2 

217.3 

3 

20.4 

7 

59.9 

1 

99.4 

5 

138.9 

9 

178.4 

3 

217.9 

4 

21.0 

S 

60.5 

2 

100.0 

6 

139.5 

290 

179.0  i 

4 

218.5 

5 

21.6 

9 

61.1 

8 

100.6 

7 

140.1 

l 

179.6 

5 

219.1 

6 

22.2 

1OO 

61.7 

4 

101.2 

8 

140.7 

2 

180.2 

6 

219.7 

7 

22.8 

1 

62.8 

5 

101.8 

9 

141.4 

3 

180.9 

7 

220.4 

8 

23.5 

2 

63.0 

6 

102.5 

230 

142.0 

4 

181.5 

S 

221.0 

9 

24.1 

8 

63.6 

7 

103.1 

1 

142.6 

5 

182.1 

9 

221.6 

40 

24.7 

4 

64.2 

8 

103.7 

2 

143.2 

6 

182.  7 

360 

222.2 

1 

25.8 

5 

64.8 

9 

104.3 

8 

143.8 

7 

183.3 

1 

222.8 

2 

25.9 

6 

65.4 

170 

104.9 

4 

144.4 

8 

183.9 

2 

223.4 

8 

26.5 

7 

66.0 

1 

105.5 

5 

145.1 

9 

184.6 

3 

224.1 

4 

27.1 

8 

667 

2 

106.2 

6 

145.7 

300 

185.2 

4 

224.7 

5 

27.8 

9 

67.3 

3 

106.8 

7 

146.3 

1 

185.8 

5 

225.8 

6 

28.4 

110 

67.9 

4 

107.4 

8 

146.9 

2 

1S6.4 

(j 

225.9 

7 

29.0 

1 

68.5 

5 

10S.O 

9 

147.5 

3 

187.0 

7 

226.5 

8 

29.6 

2 

69.1 

6 

108.6 

240 

148.1 

4 

187.6 

8 

227.1 

9 

30.2 

8 

69.7 

7 

109.3 

1 

148.  8 

5 

188.3 

9 

227.8 

50 

30.9 

4 

70.4 

8 

109.9 

2 

149.4 

6 

1S8.9 

C7O 

228.4 

1 

31.5 

5 

71.0 

9 

110.5 

8 

150.0 

7 

1S9.5 

1 

229.0 

2 

82.1 

6 

71.6 

180 

111.1 

4 

150.6 

8 

190.1 

2 

229.6 

8 

32.7 

7 

72.2 

1 

111.7 

5 

151.2 

9 

190.7 

8 

230.2 

4 

83.3 

8 

72.8 

2 

112.3 

6 

151.8 

31O 

191.3 

4 

230.8 

5 

33.9 

9 

73.4 

3 

112.9 

7 

152.4 

1 

192.0 

5 

281.5 

6 

84.6 

120 

74.1 

4 

113.6 

8 

153.1 

2 

192.6 

6 

232.1 

7 

35.2 

1 

74.7 

5 

114.2 

9 

153.7 

8 

193.2 

7 

232.7 

8 

35.8 

2 

753 

6 

114.8 

250 

154.3 

4 

193.8 

8 

233.8 

9 

36.4 

3 

75.9 

7 

115.4 

1 

154.9 

5 

194.4 

9 

233.9 

6O 

87.0 

4 

76.5 

8 

116.0 

2 

155.5 

6 

195.1 

380 

1 

37.6 

5 

77.2 

9 

116.7 

3 

156.2 

7 

195.7 

1 

235/2 

2 

38.3 

6 

77.8 

190 

117.3 

4 

156.8 

8 

196.3 

2 

235.8 

3 

38.9 

7 

78.4 

1 

117.9 

5 

157.4 

9 

196.9 

3 

236.4 

4 

39.5 

8 

79.0 

2 

118.5 

6 

158.0 

320 

197.5 

4 

237.0 

162 


PEINCIPLES   AND   PKACTICE   OF 


AUXILIARY  TO  TABLE   IV. 


WHEN     THE     AREAS     CONTAIN     DECIMAL     PARTS. 


Decimal  of  Areas. 

Decimal 
Cubic  Yards 
Corresponding. 

.00 

.0 

.17 

.1 

.33 

.2 

.50 

.3 

.66 

.4 

.83 

.5 

1.00 

.6 

N.B. — When  the  square  area  consists  of  a  whole  number  and  of 
decimal  parts  of  a  whole  number,  the  cubic  yards  corresponding  to  those 
decimal  parts,  as  given  in  the  subjoined  Auxiliary  Table,  are  to  be  added 
to  the  cubic  yards  corresponding  to  the  whole  number  as  set  forth  in 
Table  IV. 


PKINCIPLES    AND   PEACTICE   OF 


163 


TABLE   IV.— ( Continued. ) 
Table  of  Cubic  Yards  corresponding  to  Areas  in  square  feet. 


^.reaS 
uare  feet. 

ic  yards 

spending. 

1  2 

if 

»! 

£• 

is 

S.  cS 

|| 
|| 

1 
|| 

|| 
g| 

ll 

cr  ^ 

*p.9 
o  ft 

2 
is 

n'c  yards 
spending. 

"5T 

6S 

~ 

•2  S 
^8 

*s 

a. 

*! 

.2" 

if 

.5 

^8 

""sr 

a 

og 

5 

237.6 

9 

2TT.2 

8 

316.6 

7 

356.1 

1 

395.7 

5 

435.2 

6 

288.  2 

450 

27T.8 

4 

817.3 

8 

356.7 

2 

396.3 

6 

435.8 

7 

238.9 

1 

278.4 

5 

817.9 

9 

357.3 

3 

3969 

7 

436.4 

8 

239.5 

2 

279.0 

6 

318.5 

58O 

358.0 

4 

3975 

8 

437.0 

9 

240.1 

3 

279.6 

7 

319.1 

1 

358.6 

5 

398.1 

9 

437.6 

390 

240.7 

4 

280.2 

8 

319.7 

2 

359.2 

6 

398.7 

710 

438.3 

1 

241.3 

5 

280.9 

9 

320.3 

3 

359.8 

7 

399.4 

1 

438.9 

2 

241.9 

6 

281.5 

520 

321.0 

4 

360.4 

8 

400.0 

2 

439.5 

3 

242.6 

7 

282.1 

1 

321.6 

5 

361.0 

9 

400.6 

8 

440.1 

4 

2432 

8 

282.7 

2 

322.2 

6 

861.7 

650 

401.2 

4 

440.7 

5 

243.8 

9 

283.3 

ft 

322.8 

7 

362.3 

1 

401.8 

5 

441.3 

6 

244.4 

460 

283.9 

4 

323.4 

8 

362.9 

2 

402.4 

6 

442.0 

7 

245.0 

1 

284.6 

5 

324.0 

9 

863.5 

3 

403.1 

7 

442.6 

8 

245.7 

2 

285.2 

6 

824.7 

590 

364.1 

4 

403.7 

8 

443.2 

9 

246.8 

3 

285.8 

7 

325.3 

1 

364.7 

5 

404.3 

9 

443.8 

400 

246.9 

4 

28(5.4 

8 

825.9 

2 

865.4 

6 

4049 

720 

444.4 

1 

247.5 

5 

287.0 

9 

326.5 

3 

866.0 

7 

405.5 

1 

445.0 

2 

248.1 

6 

287.6 

530 

327.1 

4 

366.6 

8 

406.1 

2 

445.7 

8 

248.7 

7 

2S8.8 

1 

&27.7 

5 

867-3 

9 

406.8 

3 

446.8 

4 

249.4 

8 

288.9 

2 

328.4 

6 

367.9 

66O 

407.4 

4 

446.9 

5 

250.0 

9 

289.5 

8 

329.0 

7 

368.5 

1 

408.0 

5 

447.5 

6 

250.6 

470 

290.1 

4 

329.6 

8 

369.1 

2 

408.6 

6 

448.1 

7 

251.2 

1 

290.7 

5 

330.2 

9 

369.T 

3 

409.2 

7 

448.7 

8 

251.8 

2 

291.3 

6 

830.8 

600 

370.4 

4 

4C9.8 

8 

449.4 

9 

252.4 

3 

292.0 

7 

831.4 

1 

871-0 

5 

410.5 

9 

450.0 

410 

253.1 

4 

292.6 

8 

332.1 

2 

371.6 

6 

411.1 

730 

450.6 

1 

253.7 

5 

292.2 

9 

832.7 

3 

372.2 

7 

4117 

1 

451.2 

2 

254.3 

6 

293.8 

540 

333.3 

4 

372.8 

8 

4123 

2 

451.8 

3 

254.9 

7 

294.4 

1 

333.9 

5 

373.4 

9 

413.0 

3 

452.4 

4 

255.5 

8 

295.0 

2 

334.5 

6 

374.1 

67O 

413.6 

4 

458.1 

5 

256.2 

9 

295.T 

3 

335.1 

7 

874.7 

1 

414.3 

5 

453.7 

6 

256.8 

480 

29G.3 

4 

335.8 

8 

875.3 

2 

414.9 

6 

454.3 

7 

257.4 

1 

296.9 

5 

336.4 

9 

375.9 

3 

415.5 

7 

454.9 

8 

258.0 

2 

297.5 

6 

337.0 

610 

376.5 

4 

416.1 

8 

455.5 

9 

258.6 

3 

298.1 

7 

337.6 

1 

377.2 

5 

416.7 

9 

456.1 

42O 

259.2 

4 

298.8 

8 

338.2 

2 

377.8 

6 

417.3 

740 

456.8 

1 

259.9 

5 

2994 

9 

338.8 

8 

378.4 

7 

417.9 

1 

457.4 

2 

260.5 

6 

300.0 

550 

339.5 

4 

879.0 

8 

418.5 

2 

458.0 

3 

261.1 

7 

300.0 

1 

840.1 

5 

379.6 

9 

419.1 

3 

458.6 

4 

261.7 

8 

801.2 

2 

340.7 

6 

8802 

680 

419.7 

4 

459.2 

5 

262.3 

9 

301.8 

3 

341.3 

7 

880.  9 

1 

420.4 

5 

459.8 

6 

202.9 

490 

302.5 

4 

341.9 

8 

381.5 

2 

421-0 

6 

460.5 

7 

263.6 

1 

303.1 

5 

342.5 

9 

382.  1 

3 

421.6 

7 

461.1 

8 

264.2 

2 

303.7 

6 

843.2 

620 

382.7 

4 

422.2 

8 

461.7 

9 

264.8 

3 

304.3 

7 

343.8 

1 

383.3 

5 

422.8 

9 

462.3 

43O 

265.4 

4 

304.9 

8 

8444 

2 

883.9 

6 

423.4 

750 

463.0 

1 

266.0 

5 

305.5 

9 

345.0 

3 

384.6 

7 

424.1 

1 

463.6 

2 

266.7 

6 

806.2 

560 

345.6 

4 

885.2 

S 

424.7 

2 

464.2 

8 

267.3 

7 

306.8 

1 

346.2 

5 

385.8 

9 

425.3 

3 

464.8 

4 

267.9 

8 

807.4 

2 

346.9 

6 

386.4 

690 

425.9 

4 

465.4 

5 

268.5 

9 

308.0 

3 

847.5 

7 

387.0 

1 

426.5 

5 

466.0 

6 

269.1 

500 

308.6 

4 

348.1 

8 

387.6 

2 

427.2 

6 

466.7 

7 

269.7 

1 

309.2 

5 

348.7 

9 

388.3 

8 

4278 

7 

467.3 

8 

270.4 

2 

809.9 

6 

349.3 

630 

888.9 

4 

428.4 

8 

467.9 

9 

271.0 

8 

310.5 

7 

349.9 

1 

389.5 

5 

429.0 

9 

468.5 

44O 

271.6 

4 

311.1 

8 

350.6 

2 

390.1 

6 

429.6 

760 

469.1 

1 

272.2 

5 

311.7 

9 

351.2 

3 

390.7 

7 

430.2 

1 

469.7 

2 

272.8 

6 

312.3 

570 

351.8 

4 

391.3 

8 

430.9 

2 

470.4 

3 

273.4 

7 

312.9 

1 

352.4 

5 

892.0 

9 

431.5 

8 

471.0 

4 

274.1 

8 

313.6 

2 

353.0 

6 

392.6 

700 

432.1 

4 

471.6 

5 

274.7 

9 

314.2 

8 

853.6 

7 

893.2 

1 

4327 

5 

472.2 

6 

275.3 

51O 

814.8 

4 

8f>±.3 

8 

393.8 

2 

433.3 

6 

472.8 

7 

275.9 

1 

315.4 

5 

854.9 

9 

394.4 

3 

483  9 

7 

473.4 

8 

276.5 

2 

816.0 

6 

355.5 

640 

395.0 

4 

434.6 

8 

474.1 

164 


PRINCIPLES    AND   PRACTICE   OF 


AUXILIARY  TO  TABLE  IV. 


WHEN     THE     AREAS     CONTAIN      DECIMAL     PARTS. 


Decimal  of  Areas. 

Decimal 
Cubic  Yards 
Corresponding. 

.00 

.0 

.17 

.1 

.33 

.2 

.50 

.3 

.66 

A 

.83 

5 

1.00 

.6 

N.B. — When  the  square  area  consists  of  a  whole  number  and  of 
decimal  parts  of  a  whole  number,  the  cubic  yards  corresponding  to  those 
decimal  parts,  as  given  in  the  subjoined  Auxiliary  Table,  are  to  be  added 
to  the  cubic  yards  corresponding  to  the  whole  number  as  set  forth  in 
Table  IV. 


EMBANKING   LANDS   FEOM   KIVER-FLOODS. 


165 


TABLE   IV.— (Continued.) 
Table  of  Cubic  Yards  corresponding  to  Areas  in  square  feet. 


i 

a* 

« 

«g 

•B   S 

•~£ 

K    fcO 

^     3 

3> 

^ 

"S 

fci 

•£ 

a)  ti 

Areas 
in  square  f 

Cubic  yai 
correspond; 

Areas 
in  squaie  f 

«! 

^3 
£  §• 

5I 

i  " 

% 

G 

II 

6  o 

Areas 
in  square  f 

Cubic  yai 
correspond 

Areas 
in  square  f 

Cubic  yar 
correspond 

™  2 

*f 

_a 

Cubic  yai 
correspond 

9 

474.7 

3 

514.2 

1 

553.7 

1 

593.2 

5 

632.7 

9 

672.2 

770 

475.3 

4 

514.8 

8 

554.3 

2 

593.8 

6 

633.3 

1090 

672.8 

1 

475.9 

5 

515.4 

9 

554.9 

3 

594.4 

7 

633.9 

1 

673.5 

2 

476.5 

6 

516.0 

900 

555.5 

4 

595.1 

8 

634.6 

2 

674.1 

3 

477.1 

7 

516.7 

1 

556.2 

5 

595.7 

9 

635.2 

3 

674.7 

4 

477.8 

8 

517.3 

2 

556.8 

6 

596.3 

1030 

635.8 

4 

675.3 

5 

478.4 

9 

517.9 

3 

557.4 

7 

596.9 

1 

636.4 

5 

675.9 

6 

479.0 

840 

5185 

4 

558.0 

8 

597.5 

2 

637.0 

6 

676.5 

7 

479.6 

1 

519.1 

5 

553.6 

9 

598.1 

8 

637.7 

7 

677.2 

8 

480.  2 

2 

519.7 

6 

559.3 

97O 

598.8 

4 

638.3 

8 

677.8 

9 

480.8 

3 

520.4 

7 

559.9 

1 

599.4 

5 

638.9 

9 

678.4 

78O 

481.5 

4 

521.0 

8 

560.5 

2 

600.0 

6 

639.5 

1100 

679.0 

1 

482.1 

5 

521.6 

9 

561.1 

3 

600.6 

7 

640.1 

1 

679.6 

2 

4S2.7 

6 

522.2 

910 

561.7 

4 

601.2 

8 

640.7 

2 

680.2 

8 

483.3 

7 

522.8 

1 

562.3 

5 

601.8 

9 

641.4 

3 

680.9 

4 

483.9 

8 

523.4 

2 

563.0 

6 

602.5 

1040 

642.0 

4 

681.5 

5 

484.5 

9 

524.1 

3 

563.6 

7 

603.1 

1 

642.6 

5 

682.1 

6 

485.2 

85O 

52i.7 

4 

5C4.2 

8- 

603.7 

2 

643.2 

6 

682.7 

7 

485.8 

1 

525.3 

5 

564.8 

9 

604.3 

3 

643.8 

7 

683.3 

8 

486.4 

2 

525.9 

6 

565.4 

980 

604.9 

4 

644.4 

8 

683.9 

9 

487.0 

3 

526.5 

7 

566.0 

1 

605.5 

5 

645.1 

9 

684.6 

79O 

487.  0 

4 

527.1 

8 

566.7 

2 

606.2 

6 

645.7 

1110 

685.2 

1 

4S8.2 

5 

527.8 

9 

567.3 

3 

606.8 

7 

646.3 

1 

685.8 

2 

488.9 

6 

528.4 

920 

567.9 

4 

607.4 

8 

646.9 

2 

686.4 

3 

489.5 

7 

529.0 

1 

568.5 

5 

608.0 

9 

647.5 

3 

687.0 

4 

400.1 

8 

529.6 

2 

569.1 

6 

608.6 

1050 

648.1 

4 

687.7 

5 

490.7 

9 

530.2 

3 

569.7 

7 

609.3 

i 

648.8 

5 

688.3 

6 

491.4 

860 

530.8 

4 

570.4 

8 

609.9 

2 

649.4 

6 

688.9 

7 

492.0 

1 

531.5 

5 

571.0 

9 

610.5 

3 

650.0 

7 

689.5 

8 

492.0 

2 

532.1 

6 

571.6 

99O 

611.1 

4 

650.6 

8 

690.1 

9 

493.2 

8 

5327 

7 

572.2 

1 

611.7 

5 

651.2 

9 

690.7 

80O 

493.8 

4 

533.3 

8 

572.8 

612.3 

6 

'651.8 

1120 

691.4 

1 

494.4 

5 

533.9 

9 

573.4 

3 

613.0 

7 

652.5 

1 

692.0 

2 

495.1 

6 

534.5 

930 

574.1 

4 

613.6 

8 

653.1 

2 

692.6 

3 

495.7 

7 

535.2 

1 

574.7 

5 

614.2 

9 

653.7 

8 

693.2 

4 

496.3 

8 

535.8 

2 

575.3 

6 

614.8 

11060 

654.3 

4 

693.8 

5 

496.9 

9 

536.4 

3 

575.9 

7 

615.4' 

1 

654.9 

5 

694.4 

6 

497.5 

87O 

537.0 

4 

576.5 

8 

616.0 

2 

655.5 

6 

695.1 

498.1 

1 

5376 

5 

577.1 

9 

616.7 

3 

656.2 

7 

695.7 

8 

498.8 

2 

538.3 

6 

577.8 

1000 

617.3 

4 

656.8 

8 

696.3 

9 

499.4 

3 

538.9 

7 

578.4 

1 

617.9 

5 

657.4 

9 

696.9 

81O 

500.0 

4 

539.5 

8 

579.0 

2 

618.5 

6 

658.0 

113O 

697.5 

1 

500.6 

5 

540.1 

9 

579.6 

3 

619.1 

7 

658.6 

1 

698.1 

2 

501.2 

6 

5407 

94O 

5S0.2 

4 

619.8 

8 

659.3 

2 

698.8 

3 

501.8 

7 

541.4 

1 

580.8 

5 

620.4 

9 

659.9 

3 

699.4 

4 

502.5 

8 

5420 

2 

581.5 

6 

621.0 

107O 

660.5 

4 

700.0 

5 

503.1 

9 

542.6 

3 

582.1 

7 

621.6 

1 

661.1 

5 

700.6 

6 

503.7 

8SO 

543.2 

4 

5S2.7 

8 

622.2 

2 

661.7 

6 

701.2 

7 

504.3 

1 

5438 

5 

5S3.3 

9 

622.8 

3 

662.3 

7 

701.8 

8 

504.9 

2 

54M 

6 

5S3.9 

1O1O 

623.5 

4 

663.0 

8 

702.5 

9 

505.5 

3 

545.1 

7 

584.5 

1 

624.1 

5 

663.6 

9 

703.1 

82O 

506.2 

4 

5457 

8 

585.2 

2 

624.7 

6 

664.2 

114O 

703.7 

1 

506.8 

5 

546.3 

9 

585.8 

3 

625.3 

7 

664.8 

1 

704.3 

2 

507.4 

6 

5469 

95O 

586.4 

4 

625.9 

8 

665.4 

2 

704.9 

3 

508.0 

7 

5475 

1 

587.0 

5 

626.5 

9 

666.0 

3 

7055 

4 

508.6 

8 

548.1 

2 

537.6 

6 

627.2 

180O 

666.7 

4 

706.2 

5 

509.2 

9 

548.8 

3 

58S.3 

7 

627.8 

1 

667.3 

5 

706.8 

6 

509.9 

890 

549.4 

4 

5S3.9 

8 

628.4 

2 

667.9 

6 

707.4 

7 

510.5 

1 

550.0 

5 

589.5 

9 

629.0 

8 

668.5 

7 

70S.O 

8 

511.1 

2 

5506 

6 

590.1 

1O20 

629.6 

4 

669.1 

8 

708.6 

9 

511.7 

3 

5512 

7 

5907 

1 

680.2 

5 

669.8 

9 

709.3 

83O 

512.3 

4 

55ll8 

8 

591.4 

2 

630.9 

6 

670.4 

115O 

709.9 

1 

513.0 

5 

552  5 

9 

592.0 

3 

631.5 

7 

671.0 

1 

710.5 

2 

513.6 

6 

553.1 

960 

592.6 

4 

632.1 

8 

671.6 

2 

711.1 

166 


PRINCIPLES   AND   PKACTICE   OF 


AUXILIARY  TO  TABLE  IV. 


WHEN     THE     AREAS     CONTAIN     DECIMAL     PARTS. 


Decimal  of  Areas. 

Decimal 
Cubic  Yards 
Corresponding. 

.00 

.0 

.17 

.1 

.33 

.2 

.50 

.3 

.66 

.4 

.83 

.6 

1.00 

.6 

N.B. — 'When  the  square  area  consists  of  a  whole  number  and  of 
decimal  parts  of  a  whole  number,  the  cubic  yards  corresponding  to  those 
decimal  parts,  as  given  in  the  subjoined  Auxiliary  Table,  are  to  be  added 
to  the  cubic  yards  corresponding  to  the  whole  number  as  set  forth  in 
Table  IV. 


PRINCIPLES    AND   PRACTICE   OF 


167 


TABLE   TV.— (Continued.) 
Table  of  Cubic  Yards  corresponding  to  Areas  in  square  feet. 


ll 

fci 

11 

1 

•Sjj 
fcf 

•1 
1  2 

si 

•S.s 

*"  -3 

J 

i  £ 

m  M 

*"  'S 

i 

w  fcJb 

J 

§  2 

ft 

*| 

o'g. 

*| 

o  ft 

si 

*t 

ll 

ll 

*f 

l| 

"^1 

ll 

1 

°8 

g 

u  § 

S 

°s 

.2 

°8 

.9 

°s 

.9 

8 

3 

711.7 

7 

751.2 

1 

790.7 

5 

830.2 

9 

869.8 

8 

909.3 

4 

712.3 

8 

751.8 

2 

791.4 

6 

830.9 

1410 

870-4 

4 

909.9 

5 

713.0 

9 

752.5 

3 

792.0 

7 

831.5 

1 

871-0 

5 

910.5 

6 

713.6 

1220 

753.1 

4 

792.6 

8 

832.1 

2 

871-6 

6 

911.1 

7 

714.2 

1 

753.7 

5 

793.2 

9 

832.7 

3 

872-2 

7 

911.7 

8 

714.8 

2 

754.3 

6 

793.8 

1350 

833.3 

4 

872-8 

8 

912.3 

9 

715.4 

3 

754.9 

7 

794.4 

1 

833.9 

5 

873-5 

9 

913.0 

116O 

716.0 

4 

755.5 

8 

795.1 

2 

834.6 

6 

874-1 

1480 

913.6 

1 

716.7 

5 

756.2 

9 

795.7 

3 

835.2 

7 

874-7 

1 

914.2 

2 

717.3 

6 

756.8 

129O 

796.3 

4 

835.8 

8 

875-3 

2 

914.8 

3 

717.9 

7 

757.4 

1 

796.9 

5 

836.4 

9 

875-9 

3 

915.4 

4 

718.5 

8 

758.0 

2 

797.5 

6 

837.0 

1420 

876-5 

4 

916.0 

5 

719.1 

9 

758.6 

3 

798.1 

7 

837.7 

1 

877-2 

5 

916.7 

6 

719.8 

1230 

759.3 

4 

798.8 

8 

838.3 

2 

877-8 

6 

917.3 

7 

720.4 

1 

759.9 

5 

799.4 

9 

838.9 

3 

878-4 

7 

917.9 

8 

721.0 

2 

760.5 

6 

800.0 

1360 

839.5 

4 

879-0 

8 

918.5 

9 

721.6 

3 

761.1 

7 

800.6 

1 

840.1 

5 

879-6 

9 

919.1 

1170 

722.2 

4 

761.7 

8 

801.2 

2 

840.7 

6 

880-2 

1490 

919.8 

1 

722.8 

5 

762.3 

9 

801.8 

3 

841.4 

7 

880-9 

1 

920.4 

2 

723.5 

6 

763.0 

1300 

802.5 

4 

842.0 

8 

881-5 

2 

921.0 

3 

724.1 

7 

763.6 

1 

803.1 

5 

842,6 

9 

882-1 

3 

921.6 

4 

724.7 

8 

764.2 

2 

.  803.7 

6 

843.2 

143O 

882-7 

4 

922.2 

5 

725.3 

9 

764.8 

3 

804.3 

7 

843.8 

1 

883-3 

5 

922.8 

6 

725.9 

1240 

765.4 

4 

804.9 

8 

844.4 

2 

883-9 

6 

923.5 

7 

726.5 

1 

766.0 

5 

805.5 

9 

845.1 

3 

884-6 

7 

924.1 

8 

727.2 

2 

766.7 

6 

806.2 

1370 

845.7 

4 

885-2 

8 

924.7 

9 

727.8 

3 

767.3 

7 

806.8 

1 

846.3 

5 

885-8 

9 

925.3 

1180 

728.4 

4 

767.9 

8 

807.4 

2 

846.9 

6 

886-4 

1500 

925.9 

1 

729.0 

6 

768.5 

9 

808.0 

3 

847.5 

7 

887-0 

1 

926.5 

2 

729.6 

6 

769.1 

1310 

808.6 

4 

848.1 

8 

887-7 

2 

927!2 

8 

730.2 

7 

769.8 

1 

809.3 

5 

848.8 

9 

888-3 

3 

927.8 

4 

730.9 

8 

770.4 

2 

809.9 

6 

849.4 

144O 

888-9 

4 

928.4 

5 

731.5 

9 

771.0 

8 

810.5 

7 

850.0 

1 

889-5 

5 

929.0 

6 

732.1 

1250 

771.6 

4 

811.1 

8 

850.6 

2 

890-1 

6 

929.6 

7 

732.7 

1 

772.2 

5 

811.7 

9 

851.2 

3 

890-7 

7 

930.2 

8 

733.3 

2 

7728 

6 

812.3 

138O 

851.8 

4 

891-4 

8 

930.9 

9 

733.9 

3 

773.5 

7 

813.0 

1 

852.5 

5 

892-0 

9 

931.5 

119O 

734.6 

4 

774.1 

8 

813.6 

2 

853.1 

6 

892-6 

1510 

932.1 

1 

735.2 

5 

774.7 

9 

814.2 

3 

853.7 

7 

893-2 

1 

932.7 

2 

735.8 

6 

775.3 

1320 

814.8 

4 

854.3 

8 

893-8 

2 

933.3 

3 

736.4 

7 

775.9 

1 

815.4 

5 

854.9 

9 

894-4 

3 

938.9 

4 

737.0 

8 

776.5 

2 

816.0 

6 

855:5 

145O 

895-1 

4 

934.6 

5 

737.7 

9 

777.2 

3 

816.7 

7 

856.2 

1 

895-7 

5 

935.2 

6 

738.3 

1260 

777.8 

4 

817.3 

8 

856.8 

2 

896-3 

6 

935.8 

7 

738.9 

1 

778.4 

5 

817.9 

9 

857.4 

3 

896-9 

7 

936.4 

8 

739.5 

2 

779.0 

6 

818.5 

1390 

858.0 

4 

897-5 

8 

937.0 

9 

740.1 

8 

779.6 

7 

819.1 

1 

858.6 

5 

898-1 

9 

937.7 

1200 

740.7 

4 

7S0.2 

8 

819.8 

2 

859.3 

6 

898-8 

1520 

938.3 

1 

741.4 

5 

780.9 

9 

820.4 

3 

859.9 

7 

899-4 

1 

938.9 

2 

742.0 

6 

781.5 

1330 

821.0 

4 

860.5 

8 

900-0 

2 

939.5 

3 

742.6 

7 

7821 

1 

821.6 

5 

861.1 

9 

900-6 

3 

940.1 

4 

743.2 

8 

7S2.7 

2 

822.2 

6 

861.7 

1460 

901-2 

4 

940.T 

5 

743.8 

9 

783.3 

3 

822.8 

7 

862.3 

1 

901-8 

5 

941.4 

6 

744.4 

1270 

783.9 

4 

823.5 

8 

863.0 

2 

902-5 

6 

942.0 

7 

745.1 

1 

784.6 

5 

824.1 

9 

863.6 

3 

903-1 

7 

942.6 

8 

745.7 

2 

785.2 

6 

824.7 

1400 

864.2 

4 

903-7 

8 

943.2 

9 

746.3 

3 

785.8 

7 

825.3 

1 

864.8 

5 

904-3 

9 

948.8 

112O 

746.9 

4 

7S6.4 

8 

825.9 

2 

865.4 

6 

904-9 

1530 

944.4 

1 

747.5 

5 

7-7.0 

9 

826.5 

3 

866.0 

7 

905-5 

1 

945.1 

2 

748.1 

6 

787.7 

134O 

827.2 

4 

860.7 

8 

906-2 

2 

945.7 

8 

748.8 

7 

788.3 

1 

827.8 

5 

867.3 

9 

906.8 

3 

946.3 

4 

749.4 

8 

788.9 

2 

828.4 

6 

867.9 

147O 

907.4 

4 

946.9 

5 

750.0 

9 

789.5 

3 

829.0 

7 

868.5 

1 

908.0 

5 

947.5 

6 

750-6 

1280 

790.1 

4 

829.6 

8 

869.1 

2 

&03.6 

6 

948.1 

168 


PKIXCIPLES   AND   PRACTICE   OF 


AUXILIARY  TO  TABLE   IV. 


WHEN     THE     AREAS     CONTAIN     DECIMAL     PAIITS. 


Decimal  of  Areas. 

Decimal 
Cubic  Yards 
Corresponding. 

.00 

.0 

.17 

.1 

.33 

.2 

.50 

.3 

.66 

.4 

.83 

.5 

1.00 

.6 

N.B. — When  the  square  area  consists  of  a  whole  number  aud  of 
decimal  parts  of  a  whole  number,  the  cubic  yards  corresponding  to  those 
decimal  parts,  as  given  in  the  subjoined  Auxiliary  Table,  are  to  be  added 
to  the  cubic  yards  corresponding  to  the  whole  number  as  set  forth  in 
Table  IV. 


EMBANKING  LANDS  FEOM  EIVER-FLOODS. 


169 


TABLE  TV.— (Continued.) 
Table  of  Cubic  Yards  corresponding  to  Areas  in  square  feet. 


ts 

.si 

1 

0)    **> 

A 

ii 

1 

|I 

"o 

il 

I 

ll 

DC*1"* 

5  ^ 

K^ 

?"a 

5  a 

1  2 

fcl 

S  g 

fefl 

§  <» 

^"q 

Ji 

si 

<! 

2   CO 

s,i 

II 

II 

ll 

•51 

ll 

.s 

5  8 

A 

6i 

a 

68 

.a 

^8 

.s 

68 

a 

°S 

f" 

948.8 

1 

988.3 

5~ 

1027.8 

<T 

1067.3 

3 

1106.8 

7 

U4g  g 

8 

949.4 

2 

988.9 

6 

1028.4 

1730 

1067.9 

4 

1107.4 

8 

114&9 

9 

950.0 

3 

9S9.5 

7 

1029.0 

1 

1068.9 

5 

1108.0 

9 

1147.5 

154O 

950.6 

4 

990.1 

8 

1029.6 

2 

1069.1 

6 

1108.6 

1860 

1148.1 

1 

951.2 

5 

990.7 

9 

1030.2 

8 

1069.8 

7 

1109.3 

1 

1148.8 

2 

951.8 

6 

991.4 

1670 

1030.9 

4 

1070.4 

8 

1109.9 

2 

1149.4 

3 

952.5 

7 

992.0- 

1 

1031.5 

5 

1071.0 

9 

1110.5 

3 

1150.0 

4 

953.1 

8 

992.6 

2 

1032.1 

6 

1071.6 

180O 

1111.1 

4 

1150.6 

5 

953.7 

9 

993.2 

3 

1032.7 

7 

1072.2 

1 

1111.7 

5 

1151.2 

6 

954.3 

161O 

993.8 

4 

1033.3 

8 

1072.8 

2 

1112.3 

6 

1151.8 

7 

954.9 

1 

994.4 

5 

1033.9 

9 

1073.5 

8 

1118.0 

7 

1152.5 

8 

955.5 

2 

995.1 

6 

1034.6 

1740 

1074.1 

4 

1113.6 

8 

1153.1 

9 

956.2 

3 

995.7 

7 

1035.2 

1 

1074.7 

5 

1114.2 

9 

1153.7 

155O 

956.8 

4 

996.3 

8 

1035.8 

2 

1075.8 

6 

1114.8 

1870 

1154.3 

1 

957.4 

5 

996.9 

9 

1036.4 

3 

1075.9 

7 

1115.4 

1 

1154.9 

2 

958.0 

6 

997.5 

168O 

1037.0 

4 

1076.5 

8 

1116.0 

2 

1155.5 

3 

958.6 

7 

998.1 

1 

1037.7 

5 

1077.2 

9 

1116.7 

8 

1156.2 

4 

959.8 

8 

998.8 

2 

1038.3 

6 

1077.8 

181O 

1117.8 

4 

1156.8 

5 

959.9 

9 

999.4 

3 

1038.9 

7 

1078.4 

1 

1117.9 

5 

1157.4 

6 

960.5 

1620 

1000.0 

4 

1039.5 

8 

1079.0 

2 

1118-5 

6 

1158.0 

7 

961.1 

1 

1000.6 

5 

1040-1 

9 

1079.6 

8 

1119.1 

7 

1158.6 

8 

961.7 

2 

1001.2 

6 

1040-7 

1750 

10S0.2 

4 

1119.8 

8 

1159.3 

9 

962.3 

3 

1001.8 

7 

1041-4 

1 

1080.9 

5 

1120.4 

9 

1159.9 

156O 

963.0 

4 

1002.5 

8 

1042-0 

2 

1081-5 

6 

1121.0 

1880 

1160.5 

1 

963.6 

5 

1003.1 

9 

1042-6 

3 

1082-1 

7 

1121.6 

1 

1161.1 

2 

964.2 

6 

1003.7 

1690 

1043-2 

4 

1082-7 

8 

1122.2 

2 

1161.7 

3 

964.8 

7 

1004.3 

1 

1043-8 

5 

1083.3 

9 

1122.8 

8 

1162.3 

4 

965.4 

8 

1004.9 

2 

1044-4 

6 

1083.9 

1820 

1123.5 

4 

1163.0 

5 

966.0 

9 

1005.5 

3 

1045-1 

7 

1084.6 

1 

1124.1 

5 

1163.6 

6 

9667 

163O 

1006.2 

4 

1045-7 

8 

1085.2 

2 

1124.7 

6 

1164.2 

7 

967.3 

1 

1006.8 

5 

1046-3 

9 

1085-8 

8 

1125.3 

7 

1164.8 

8 

967.9 

2 

1007.4 

6 

1046-9 

176O 

1086.4 

4 

1125.9 

8 

1165.4 

9 

968.5 

3 

1008.0 

1047-5 

1 

1087-0 

5 

1126.5 

9 

1166.0 

157O 

969.1 

4 

1003.6 

8 

1048-1 

2 

1087-7 

6 

1127.2 

1890 

1166.7 

1 

969.8 

5 

1009.3 

9 

1048-8 

3 

1088-3 

7 

1127.8 

1 

1167.3 

2 

970.4 

6 

1009.9 

1700 

1049-4 

4 

10S8-9 

8 

1128.4 

2 

1167.9 

8 

971.0 

7 

1010.5 

1 

1050-0 

5 

1089-5 

9 

1129.0 

3 

1168.5 

4 

971.6 

8 

1011.1 

2 

1050-6 

6 

1090-1 

1830 

1129.6 

4 

1169.1 

5 

972.2 

9 

1011.7 

3 

1051-2 

7 

1090-7 

1 

1130.2 

5 

1169.8 

6 

972.8 

164O 

1012.3 

4 

1051-8 

8 

1091.4 

2 

1130.9 

6 

1170.4 

7 

978.5 

1 

1013.0 

5 

1052-5 

9 

1092.0 

1131.5 

7 

1171.0 

8 

974.1 

2 

1013.6 

6 

1053-1 

177O 

1092.6 

4 

1132.1 

8 

1171.6 

9 

974.7 

3 

1014.2 

7 

1053-7 

1 

1093.2 

5 

1132.7 

9 

1172.2 

158O 

975.3 

4 

1014.8 

8 

1054-3 

2 

1093.8 

6 

1133.3 

1900 

1172.8 

1 

975.9 

5 

1015.4 

9 

1054.9 

8 

1094.4 

7 

1133-9 

1 

1173.5 

2 

976.5 

6 

1016.0 

1710 

1055-5 

4 

1095.1 

8 

1184.6 

2 

1174.1 

8 

977.2 

7 

1016.7 

1 

1056-2 

5 

1095.7 

9 

1135.2 

8 

1174.7 

4 

977.3 

8 

1017.3 

2 

1056-8 

6 

1096.3 

184O 

1135.8 

4 

1175.3 

5 

973.4 

9 

1017.9 

3 

1057-4 

7 

1096-9 

1 

1136.4 

5 

1175.9 

6 

979.0 

165O 

1018.5 

4 

1058-0 

8 

1097-5 

2 

1137.0 

6 

1176.5 

7 

979.6 

1 

1019.1 

5 

1058-6 

9 

1098.1 

3 

1137.7 

7 

1177.2 

8 

980.2 

2 

1019.8 

6 

1059-3 

178O 

1098.8 

4 

1138.3 

8 

1177.8 

9 

9S0.9 

3 

1020.4 

7 

1059-9 

1 

1099.4 

5 

1138.9 

9 

1178.4 

159O 

981.5 

4 

1021.0 

8 

1060-5 

2 

1100.0 

6 

1139.5 

191O 

1179.0 

1 

982.1 

5 

1021.6 

9 

1061.1 

3 

1100-6 

7 

1140.1 

1 

1179.6 

2 

982.7 

6 

1022.2 

1720 

1061-7 

4 

1101.2 

8 

1140.7 

2 

1180.2 

3 

9S3.3 

7 

1022.8 

1 

1062-3 

5 

1101.8 

9 

1141.4 

8 

1180.9 

4 

9S3.9 

8 

1023.5 

2 

1063.0 

6 

1102.5 

185O 

1142.0 

4 

1181.5 

5 

984.6 

9 

1024.1 

3 

1063.6 

7 

1103.1 

1 

1142.6 

5 

1182.1 

o 

985.2 

166O 

1024.7 

4 

1064.2 

8 

1103.7 

2 

1143.2 

6 

1182.7 

7 

935.8 

1 

1025.8 

5 

1064.8 

9 

1104.3 

3 

1143.8 

7 

1183.3 

8 

9S6.4 

2 

1025.9 

6 

1065.4 

179O 

1104.9 

4 

1144.4 

8 

1183.9 

9 

987.0 

3 

1026.5 

7 

1066.1 

1 

1105.5 

5 

1145.1 

9 

1184.6 

160U 

987.7 

4 

1027.2 

8 

1066.7 

2 

1106.2 

6 

1145.7 

192O 

1185.2 

170 


PRINCIPLES   AND  PRACTICE  OF 


AUXILIARY  TO  TABLE  IV. 


WHEN     THE     AREAS     CONTAIN     DECIMAL     PARTS. 


Decimal  of  Areas. 

Decimal 
Cubic  Yards 
Corresponding. 

.00 

.0 

.17 

.1 

.33 

.2 

.60 

.3 

.66 

.4 

.83 

.6 

1.00 

.6 

N.B. — When  the  square  area  consists  of  a  whole  number  and  of 
decimal  parts  of  a  whole  number,  the  cubic  yards  corresponding  to  those 
decimal  parts,  as  given  in  the  subjoined  Auxiliary  Table,  are  to  be  added 
to  the  cubic  yards  corresponding  to  the  whole  number  as  set  forth  in 
Table  IY. 


PRINCIPLES   AND  PEACTICE  OF 


171 


TABLE  IV.— (Continued.) 
Table  of  Cubic  Yards  corresponding  to  Areas  in  square  feet. 


J 

K    k* 

•3  2 
<=-a 

J 

to  taO 

•o.S 
£13 

•s 

a 

tJo 

rn  ~ 

1^ 

1 

•§1 

1 

tb 

-S.S 

1 

•gl 

1| 
*I 

.5 

Cubic  ys 
correspon 

Areas 
in  square 

Cubic  yf 
correspon 

Area! 
in  square 

£1 

11 

°s 

B  0> 
£S 

X| 

.9 

Cubic  ys 
correspou 

5  £ 
<f 

Cubic  yf 
correspou 

Is 

<! 

Cubic  yf 
correspon 

1 

1185.8 

2 

1217.3 

8 

1248.8 

4 

1280.2 

5 

1311.7 

e 

1343.2 

2 

11S6.4 

3 

1217.9 

4 

1249.4 

«. 

1280.9 

6 

1812.3 

i 

1343.8 

3 

1187.0 

4 

1218.5 

5 

1250.0 

6 

12S1.5 

*j 

1313.0 

8 

1344.4 

4 

1187.7 

5 

1219.1 

6 

1250.6 

7 

1282.1 

8 

1313.6 

9 

1345.1 

5 

1188.3 

6 

1219.8 

7 

1251.2 

8 

1282.7 

9 

1314.2 

218O 

1345.T 

6 

11SS.9 

7 

1220.4 

8 

1251.8 

9 

1283.3 

2130 

1314.8 

1 

1346.3 

7 

11S9.5 

8 

1221.0 

9 

1252.5 

208O 

1283.9 

1 

1315.4 

2 

1346.9 

8 

1190.1 

9 

1221.6 

2030 

1253.1 

1 

12S4.6 

s 

1316.0 

3 

1347.5 

9 

1190.7 

198O 

1222.2 

1 

1253.7 

2 

1285.2 

3 

1316.7 

4 

1348.1 

193O 

1191.4 

1 

1222.8 

2 

1254.3 

3 

1285.8 

4 

1317.3 

5 

1348.8 

1 

1192.0 

2 

1223.5 

3 

1254.9 

4 

1286.4 

5 

1317.9 

6 

1349.4 

2 

1192.6 

8 

1224.1 

4 

1255.6 

5 

1287.0 

6 

1318.5 

7 

1850.0 

3 

1193.2 

4 

1224.7 

5 

1256.2 

6 

1287.7 

7 

1319.1 

8 

1350.6 

4 

1193.8 

5 

1225.3 

6 

1256.8 

7 

128S.3 

8 

1319.8 

9 

1351.2 

5 

1194.4 

6 

1225.9 

7 

1257.4 

8 

1288.9 

9 

1320.4 

219O 

1351.8 

6 

1195.1 

7 

1226.5 

8 

1258.0 

9 

1289.5 

2140 

1321.0 

1 

1352.5 

7 

1195.7 

8 

1227.2 

9 

1258.6 

2090 

1290.1 

1 

1321.6 

2 

1353.1 

8 

1196.3 

9 

1227.8 

204O 

1259.3 

1 

129Q.7 

2 

1822.2 

3 

1353.7 

9 

1196.9 

1990 

1228.4 

1 

1259.9 

2 

1291.4 

3 

1322.8 

4 

1354.3 

1940 

1197,5 

1 

1229.0 

2 

1260.5 

3 

1292.0 

4 

1323.5 

5 

1354.9 

1 

1198.1 

2 

1229.6 

8 

1261.1 

4 

1292.6 

5 

1824.1 

6 

1355.6 

2 

1198.8 

8 

1230.2 

4 

1261.7 

5 

1293.2 

6 

1324.7 

7 

1356.2 

8 

1199.4 

4 

1230.9 

5 

1262.3 

6 

1293.8 

7 

1325.3 

8 

1356.8 

4 

1200.0 

5 

1231.5 

6 

1263.0 

7 

1294.4 

8 

1825.9 

9 

1357.4 

5 

1200.6 

6 

1232.1 

7 

1263.6 

8 

1295.1 

9 

1326.5 

220O 

1358.0 

6 

1201.2 

T 

1232.7 

8 

1264.2 

9 

1295.7 

215O 

1327.2 

1 

1358.6 

7 

1201.8 

8 

1233.3 

9 

1264.8 

2100 

1296.3 

1 

1327.8 

2 

1859.3 

8 

1202.5 

9 

1233.9 

205O 

1265.4 

1 

1296.9 

2 

1328.4 

8 

1359.9 

9 

1203.1 

200O 

1234.6 

1 

1266.0 

2 

1297.5 

3 

1329.0 

4 

1860.5 

1950 

1203.7 

1 

1235.2 

2 

1266.7 

8 

1298.1 

4 

1829.6 

5 

1861.1 

1 

1204.3 

2 

1235.8 

8 

1267.3 

4 

1298.8 

5 

1330.2 

6 

1361.7 

2 

1204.9 

8 

1236.4 

4 

1267.9 

5 

1299.4 

6 

1330.9 

7 

362.3 

8 

1205.6 

4 

1237.0 

5 

1268.5 

6 

1300.0 

7 

331.5 

8 

363.0 

4 

1206.2 

5 

1237.7 

6 

1269.1 

7 

1300.6 

8 

332.1 

9 

363.6 

5 

1206.8 

6 

1238.3 

7 

1269.8 

8 

1301.2 

9 

332.7 

21O 

364.2 

6 

1207.4 

T 

1238.9 

8 

1270.4 

9 

301.8 

160 

383.3 

1 

364.8 

7 

1208.0 

8 

1289.5 

9 

1271.0 

211O 

302.5 

1 

388.9 

2 

365.4 

8 

1208.  6 

9 

1240.1 

06O 

1271.6 

1 

303.1 

2 

834.6 

3 

366.0 

9 

1209.3 

2O1O 

1240.7 

1 

1272.2 

2 

303.7 

8 

335.2 

4 

366.7 

I960 

1209.9 

1 

1241.4 

2 

272.8 

3 

804.3 

4 

335.8 

5 

367.3 

1 

1210.5 

2 

1242.0 

8 

273.5 

4 

804.9 

5 

336.4 

6 

367.9 

2 

1211.1 

8 

1242.6 

4 

274.1 

5 

305.6 

6 

837.0 

7 

368.5 

3 

1211.7 

4 

1243.2 

5 

274.7 

6 

306.2 

7 

337.7 

8 

369.1 

4 

1212.3 

5 

1248.8 

6 

275.3 

7 

306.8 

8 

338.3 

9 

369.8 

5 

1213.0 

6 

1244.4 

7 

275.9 

8 

307.4 

9 

338.9 

22O 

370.4 

6 

1213.6 

7 

1245.1 

8 

276.5 

9 

308.0 

17O 

839.5 

1 

371.0 

7 

1214.2 

8 

1245.7 

9 

277.2 

212O 

308.6 

1 

840.1 

2 

871.6 

8 

1214.8 

9 

246.3 

07O 

277.8 

1 

309.3 

2 

340.7 

8 

372.2 

9 

1215.4 

020 

246.9 

1 

278.4 

2 

809.9 

3 

341.4 

4 

372.8 

197O 

1216.0 

1 

247.9 

279.0 

3 

810.5 

4 

342.0 

5 

373.5 

1 

1216.7 

2 

1248.1 

3 

279.6 

4 

811.1 

5 

842.6 

6 

374.1 

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